EPA 200.8
METHOD 200.8
DETERMINATION OF TRACE ELEMENTS IN WATERS AND WASTES
BY INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY
Revision 5.4
EMMC Version
S.E. Long (Technology Applications Inc.), T.D. Martin, and E.R. Martin - Method 200.8,
Revisions 4.2 and 4.3 (1990)
S.E. Long (Technology Applications Inc.) and T.D. Martin - Method 200.8, Revision 4.4 (1991)
J.T. Creed, C.A. Brockhoff, and T.D. Martin - Method 200.8, Revision 5.4 (1994)
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
METHOD 200.8
200.8-1
DETERMINATION OF TRACE ELEMENTS IN WATERS AND WASTES
BY INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY
1.0
SCOPE AND APPLICATION
1.1
This method provides procedures for determination of dissolved elements in
ground waters, surface waters and drinking water. It may also be used for
determination of total recoverable element concentrations in these waters as well
as wastewaters, sludges and soils samples. This method is applicable to the
following elements:
Chemical Abstract Services
Registry Number (CASRN)
Analyte
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
(Al)
(Sb)
(As)
(Ba)
(Be)
(Cd)
(Cr)
(Co)
(Cu)
(Pb)
(Mn)
(Hg)
(Mo)
(Ni)
(Se)
(Ag)
(Tl)
(Th)
(U)
(V)
(Zn)
7429-90-5
7440-36-0
7440-38-2
7440-39-3
7440-41-7
7440-43-9
7440-47-3
7440-48-4
7440-50-8
7439-92-1
7439-96-5
7439-97-6
7439-98-7
7440-02-0
7782-49-2
7440-22-4
7440-28-0
7440-29-1
7440-61-1
7440-62-2
7440-66-6
Estimated instrument detection limits (IDLs) for these elements are listed in
Table 1. These are intended as a guide to instrumental limits typical of a system
optimized for multielement determinations and employing commercial
instrumentation and pneumatic nebulization sample introduction. However,
actual method detection limits (MDLs) and linear working ranges will be
dependent on the sample matrix, instrumentation and selected operating
conditions. Given in Table 7 are typical MDLs for both total recoverable
determinations by "direct analysis" and where sample digestion is employed.
200.8-2
1.2
For reference where this method is approved for use in compliance monitoring
programs [e.g., Clean Water Act (NPDES) or Safe Drinking Water Act (SDWA)]
consult both the appropriate sections of the Code of Federal Regulation (40 CFR
Part 136 Table 1B for NPDES, and Part 141 § 141.23 for drinking water), and the
latest Federal Register announcements.
1.3
Dissolved elements are determined after suitable filtration and acid preservation.
In order to reduce potential interferences, dissolved solids should not exceed
0.2% (w/v) (Section 4.1.4).
1.4
With the exception of silver, where this method is approved for the determination
of certain metal and metalloid contaminants in drinking water, samples may be
analyzed directly by pneumatic nebulization without acid digestion if the samples
have been properly preserved with acid and have turbidity of <1 NTU at the time
of analysis. This total recoverable determination procedure is referred to as
"direct analysis".
1.5
For the determination of total recoverable analytes in aqueous and solid samples
a digestion/extraction is required prior to analysis when the elements are not in
solution (e.g., soils, sludges, sediments and aqueous samples that may contain
particulate and suspended solids). Aqueous samples containing suspended or
particulate material ≥1% (w/v) should be extracted as a solid type sample
(Section 11.2.2).
1.6
The total recoverable sample digestion procedure given in this method is not
suitable for the determination of volatile organo-mercury compounds. However,
for "direct analysis" of drinking water (turbidity <1 NTU), the combined
concentrations of inorganic and organo-mercury in solution can be determined by
"direct analysis" pneumatic nebulization provided gold is added to both samples
and standards alike to eliminate memory interference effects.
1.7
Silver is only slightly soluble in the presence of chloride unless there is a
sufficient chloride concentration to form the soluble chloride complex. Therefore,
low recoveries of silver may occur in samples, fortified sample matrices and even
fortified blanks if determined as a dissolved analyte or by "direct analysis" where
the sample has not been processed using the total recoverable mixed acid
digestion. For this reason it is recommended that samples be digested prior to
the determination of silver. The total recoverable sample digestion procedure
given in this method is suitable for the determination of silver in aqueous samples
containing concentrations up to 0.1 mg/L. For the analysis of wastewater
samples containing higher concentrations of silver, succeeding smaller volume,
well mixed sample aliquots must be prepared until the analysis solution contains
<0.1 mg/L silver. The extraction of solid samples containing concentrations of
silver >50 mg/kg should be treated in a similar manner.
1.8
The total recoverable sample digestion procedure given in this method will
solubilize and hold in solution only minimal concentrations of barium in the
presence of free sulfate. For the analysis of barium in samples having varying
200.8-3
and unknown concentrations of sulfate, analysis should be completed as soon as
possible after sample preparation.
2.0
3.0
1.9
This method should be used by analysts experienced in the use of inductively
coupled plasma mass spectrometry (ICP-MS), the interpretation of spectral and
matrix interferences and procedures for their correction. A minimum of six
months experience with commercial instrumentation is recommended.
1.10
Users of the method data should state the data-quality objectives prior to analysis.
Users of the method must document and have on file the required initial
demonstration performance data described in Section 9.2 prior to using the
method for analysis.
SUMMARY OF METHOD
2.1
An aliquot of a well mixed, homogeneous aqueous or solid sample is accurately
weighed or measured for sample processing. For total recoverable analysis of a
solid or an aqueous sample containing undissolved material, analytes are first
solubilized by gentle refluxing with nitric and hydrochloric acids. After cooling,
the sample is made up to volume, is mixed and centrifuged or allowed to settle
overnight prior to analysis. For the determination of dissolved analytes in a
filtered aqueous sample aliquot, or for the "direct analysis" total recoverable
determination of analytes in drinking water where sample turbidity is <1 NTU,
the sample is made ready for analysis by the appropriate addition of nitric acid,
and then diluted to a predetermined volume and mixed before analysis.
2.2
The method describes the multi-element determination of trace elements by ICPMS.1-3 Sample material in solution is introduced by pneumatic nebulization into
a radiofrequency plasma where energy transfer processes cause desolvation,
atomization and ionization. The ions are extracted from the plasma through a
differentially pumped vacuum interface and separated on the basis of their massto-charge ratio by a quadrupole mass spectrometer having a minimum resolution
capability of 1 amu peak width at 5% peak height. The ions transmitted through
the quadrupole are detected by an electron multiplier or Faraday detector and the
ion information processed by a data handling system. Interferences relating to
the technique (Section 4.0) must be recognized and corrected for. Such corrections
must include compensation for isobaric elemental interferences and interferences
from polyatomic ions derived from the plasma gas, reagents or sample matrix.
Instrumental drift as well as suppressions or enhancements of instrument
response caused by the sample matrix must be corrected for by the use of internal
standards.
DEFINITIONS
3.1
Calibration Blank - A volume of reagent water acidified with the same acid
matrix as in the calibration standards. The calibration blank is a zero standard
and is used to calibrate the ICP instrument (Section 7.6.1).
200.8-4
3.2
Calibration Standard (CAL) - A solution prepared from the dilution of stock
standard solutions. The CAL solutions are used to calibrate the instrument
response with respect to analyte concentration (Section 7.4).
3.3
Dissolved Analyte - The concentration of analyte in an aqueous sample that will
pass through a 0.45 µm membrane filter assembly prior to sample acidification
(Section 11.1).
3.4
Field Reagent Blank (FRB) - An aliquot of reagent water or other blank matrix
that is placed in a sample container in the laboratory and treated as a sample in
all respects, including shipment to the sampling site, exposure to the sampling
site conditions, storage, preservation, and all analytical procedures. The purpose
of the FRB is to determine if method analytes or other interferences are present
in the field environment (Section 8.5).
3.5
Instrument Detection Limit (IDL) - The concentration equivalent to the analyte
signal which is equal to three times the standard deviation of a series of 10
replicate measurements of the calibration blank signal at the selected analytical
mass(es). (Table 1).
3.6
Internal Standard - Pure analyte(s) added to a sample, extract, or standard
solution in known amount(s) and used to measure the relative responses of other
method analytes that are components of the same sample or solution. The
internal standard must be an analyte that is not a sample component (Sections 7.5
and 9.4.5).
3.7
Laboratory Duplicates (LD1 and LD2) - Two aliquots of the same sample taken
in the laboratory and analyzed separately with identical procedures. Analyses of
LD1 and LD2 indicates precision associated with laboratory procedures, but not
with sample collection, preservation, or storage procedures.
3.8
Laboratory Fortified Blank (LFB) - An aliquot of LRB to which known quantities
of the method analytes are added in the laboratory. The LFB is analyzed exactly
like a sample, and its purpose is to determine whether the methodology is in
control and whether the laboratory is capable of making accurate and precise
measurements (Sections 7.9 and 9.3.2).
3.9
Laboratory Fortified Sample Matrix (LFM) - An aliquot of an environmental
sample to which known quantities of the method analytes are added in the
laboratory. The LFM is analyzed exactly like a sample, and its purpose is to
determine whether the sample matrix contributes bias to the analytical results.
The background concentrations of the analytes in the sample matrix must be
determined in a separate aliquot and the measured values in the LFM corrected
for background concentrations (Section 9.4).
3.10
Laboratory Reagent Blank (LRB) - An aliquot of reagent water or other blank
matrices that are treated exactly as a sample including exposure to all glassware,
equipment, solvents, reagents, and internal standards that are used with other
samples. The LRB is used to determine if method analytes or other interferences
200.8-5
are present in the laboratory environment, reagents, or apparatus (Sections 7.6.2
and 9.3.1).
4.0
3.11
Linear Dynamic Range (LDR) - The concentration range over which the
instrument response to an analyte is linear (Section 9.2.2).
3.12
Method Detection Limit (MDL) - The minimum concentration of an analyte that
can be identified, measured, and reported with 99% confidence that the analyte
concentration is greater than zero (Section 9.2.4 and Table 7).
3.13
Quality Control Sample (QCS) - A solution of method analytes of known
concentrations which is used to fortify an aliquot of LRB or sample matrix. The
QCS is obtained from a source external to the laboratory and different from the
source of calibration standards. It is used to check either laboratory or instrument
performance (Sections 7.8 and 9.2.3).
3.14
Solid Sample - For the purpose of this method, a sample taken from material
classified as either soil, sediment or sludge.
3.15
Stock Standard Solution - A concentrated solution containing one or more
method analytes prepared in the laboratory using assayed reference materials or
purchased from a reputable commercial source (Section 7.3).
3.16
Total Recoverable Analyte - The concentration of analyte determined either by
"direct analysis" of an unfiltered acid preserved drinking water sample with
turbidity of <1 NTU (Section 11.2.1), or by analysis of the solution extract of a
solid sample or an unfiltered aqueous sample following digestion by refluxing
with hot dilute mineral acid(s) as specified in the method (Sections 11.2 and 11.3).
3.17
Tuning Solution - A solution which is used to determine acceptable instrument
performance prior to calibration and sample analyses (Section 7.7).
3.18
Water Sample - For the purpose of this method, a sample taken from one of the
following sources: drinking, surface, ground, storm runoff, industrial or domestic
wastewater.
INTERFERENCES
4.1
Several interference sources may cause inaccuracies in the determination of trace
elements by ICP-MS. These are:
4.1.1
Isobaric elemental interferences - Are caused by isotopes of different
elements which form singly or doubly charged ions of the same nominal
mass-to-charge ratio and which cannot be resolved by the mass
spectrometer in use. All elements determined by this method have, at a
minimum, one isotope free of isobaric elemental interference. Of the
analytical isotopes recommended for use with this method (Table 4), only
molybdenum-98 (ruthenium) and selenium-82 (krypton) have isobaric
elemental interferences. If alternative analytical isotopes having higher
200.8-6
natural abundance are selected in order to achieve greater sensitivity, an
isobaric interference may occur. All data obtained under such conditions
must be corrected by measuring the signal from another isotope of the
interfering element and subtracting the appropriate signal ratio from the
isotope of interest. A record of this correction process should be included
with the report of the data. It should be noted that such corrections will
only be as accurate as the accuracy of the isotope ratio used in the
elemental equation for data calculations. Relevant isotope ratios should
be established prior to the application of any corrections.
4.1.2
Abundance sensitivity - Is a property defining the degree to which the
wings of a mass peak contribute to adjacent masses. The abundance
sensitivity is affected by ion energy and quadrupole operating pressure.
Wing overlap interferences may result when a small ion peak is being
measured adjacent to a large one. The potential for these interferences
should be recognized and the spectrometer resolution adjusted to
minimize them.
4.1.3
Isobaric polyatomic ion interferences - Are caused by ions consisting of
more than one atom which have the same nominal mass-to-charge ratio
as the isotope of interest, and which cannot be resolved by the mass
spectrometer in use. These ions are commonly formed in the plasma or
interface system from support gases or sample components. Most of the
common interferences have been identified3, and these are listed in Table2
together with the method elements affected. Such interferences must be
recognized, and when they cannot be avoided by the selection of
alternative analytical isotopes, appropriate corrections must be made to
the data. Equations for the correction of data should be established at the
time of the analytical run sequence as the polyatomic ion interferences will
be highly dependent on the sample matrix and chosen instrument
conditions. In particular, the common 82Kr interference that affects the
determination of both arsenic and selenium, can be greatly reduced with
the use of high purity krypton free argon.
4.1.4
Physical interferences - Are associated with the physical processes which
govern the transport of sample into the plasma, sample conversion
processes in the plasma, and the transmission of ions through the plasmamass spectrometer interface. These interferences may result in differences
between instrument responses for the sample and the calibration
standards. Physical interferences may occur in the transfer of solution to
the nebulizer (e.g., viscosity effects), at the point of aerosol formation and
transport to the plasma (e.g., surface tension), or during excitation and
ionization processes within the plasma itself. High levels of dissolved
solids in the sample may contribute deposits of material on the extraction
and/or skimmer cones reducing the effective diameter of the orifices and
therefore ion transmission. Dissolved solids levels not exceeding
0.2% (w/v) have been recommended3 to reduce such effects. Internal
standardization may be effectively used to compensate for many physical
interference effects.4 Internal standards ideally should have similar
200.8-7
analytical behavior to the elements being determined.
4.1.5
5.0
Memory interferences - Result when isotopes of elements in a previous
sample contribute to the signals measured in a new sample. Memory
effects can result from sample deposition on the sampler and skimmer
cones, and from the buildup of sample material in the plasma torch and
spray chamber. The site where these effects occur is dependent on the
element and can be minimized by flushing the system with a rinse blank
between samples (Section 7.6.3). The possibility of memory interferences
should be recognized within an analytical run and suitable rinse times
should be used to reduce them. The rinse times necessary for a particular
element should be estimated prior to analysis. This may be achieved by
aspirating a standard containing elements corresponding to 10 times the
upper end of the linear range for a normal sample analysis period,
followed by analysis of the rinse blank at designated intervals. The length
of time required to reduce analyte signals to within a factor of 10 of the
method detection limit, should be noted. Memory interferences may also
be assessed within an analytical run by using a minimum of three
replicate integrations for data acquisition. If the integrated signal values
drop consecutively, the analyst should be alerted to the possibility of a
memory effect, and should examine the analyte concentration in the
previous sample to identify if this was high. If a memory interference is
suspected, the sample should be reanalyzed after a long rinse period. In
the determination of mercury, which suffers from severe memory effects,
the addition of 100 µg/L gold will effectively rinse 5 µg/L mercury in
approximately two minutes. Higher concentrations will require a longer
rinse time.
SAFETY
5.1
The toxicity or carcinogenicity of reagents used in this method have not been fully
established. Each chemical should be regarded as a potential health hazard and
exposure to these compounds should be as low as reasonably achievable. Each
laboratory is responsible for maintaining a current awareness file of OSHA
regulations regarding the safe handling of the chemicals specified in this
method. 5,8 A reference file of material data handling sheets should also be
available to all personnel involved in the chemical analysis. Specifically,
concentrated nitric and hydrochloric acids present various hazards and are
moderately toxic and extremely irritating to skin and mucus membranes. Use
these reagents in a fume hood whenever possible and if eye or skin contact
occurs, flush with large volumes of water. Always wear safety glasses or a shield
for eye protection, protective clothing and observe proper mixing when working
with these reagents.
5.2
The acidification of samples containing reactive materials may result in the release
of toxic gases, such as cyanides or sulfides. Acidification of samples should be
done in a fume hood.
5.3
All personnel handling environmental samples known to contain or to have been
200.8-8
in contact with human waste should be immunized against known disease
causative agents.
6.0
5.4
Analytical plasma sources emit radiofrequency radiation in addition to intense UV
radiation. Suitable precautions should be taken to protect personnel from such
hazards. The inductively coupled plasma should only be viewed with proper eye
protection from UV emissions.
5.5
It is the responsibility of the user of this method to comply with relevant disposal
and waste regulations. For guidance see Sections 14.0 and 15.0.
EQUIPMENT AND SUPPLIES
6.1 Inductively coupled plasma mass spectrometer:
6.1.1
Instrument capable of scanning the mass range 5-250 amu with a
minimum resolution capability of 1 amu peak width at 5% peak height.
Instrument may be fitted with a conventional or extended dynamic range
detection system.
Note: If an electron multiplier detector is being used, precautions should
be taken, where necessary, to prevent exposure to high ion flux.
Otherwise changes in instrument response or damage to the multiplier
may result.
6.2
6.1.2
Radio-frequency generator compliant with FCC regulations.
6.1.3
Argon gas supply - High purity grade (99.99%). When analyses are
conducted frequently, liquid argon is more economical and requires less
frequent replacement of tanks than compressed argon in conventional
cylinders (Section 4.1.3).
6.1.4
A variable-speed peristaltic pump is required for solution delivery to the
nebulizer.
6.1.5
A mass-flow controller on the nebulizer gas supply is required. A watercooled spray chamber may be of benefit in reducing some types of
interferences (e.g., from polyatomic oxide species).
6.1.6
If an electron multiplier detector is being used, precautions should be
taken, where necessary, to prevent exposure to high ion flux. Otherwise
changes in instrument response or damage to the multiplier may result.
Samples having high concentrations of elements beyond the linear range
of the instrument and with isotopes falling within scanning windows
should be diluted prior to analysis.
Analytical balance, with capability to measure to 0.1 mg, for use in weighing
solids, for preparing standards, and for determining dissolved solids in digests
or extracts.
200.8-9
6.3
A temperature adjustable hot plate capable of maintaining a temperature of 95°C.
6.4
(Optional) A temperature adjustable block digester capable of maintaining a
temperature of 95°C and equipped with 250 mL constricted digestion tubes.
6.5
(Optional) A steel cabinet centrifuge with guard bowl, electric timer and brake.
6.6
A gravity convection drying oven with thermostatic control capable of
maintaining 105°C ± 5°C.
6.7
(Optional) An air displacement pipetter capable of delivering volumes ranging
from 0.1-2500 µL with an assortment of high quality disposable pipet tips.
6.8
Mortar and pestle, ceramic or nonmetallic material.
6.9
Polypropylene sieve, 5-mesh (4 mm opening).
6.10
Labware - For determination of trace levels of elements, contamination and loss
are of prime consideration. Potential contamination sources include improperly
cleaned laboratory apparatus and general contamination within the laboratory
environment from dust, etc. A clean laboratory work area designated for trace
element sample handling must be used. Sample containers can introduce positive
and negative errors in the determination of trace elements by (1) contributing
contaminants through surface desorption or leaching, (2) depleting element
concentrations through adsorption processes. All reusable labware (glass, quartz,
polyethylene, PTFE, FEP, etc.) should be sufficiently clean for the task objectives.
Several procedures found to provide clean labware include soaking overnight and
thoroughly washing with laboratory-grade detergent and water, rinsing with tap
water, and soaking for four hours or more in 20% (V/V) nitric acid or a mixture
of dilute nitric and hydrochloric acid (1+2+9), followed by rinsing with reagent
grade water and storing clean.
Note: Chromic acid must not be used for cleaning glassware.
6.10.1 Glassware - Volumetric flasks, graduated cylinders, funnels and centrifuge
tubes (glass and/or metal free plastic).
6.10.2 Assorted calibrated pipettes.
6.10.3 Conical Phillips beakers (Corning 1080-250 or equivalent), 250 mL with
50 mm watch glasses.
6.10.4 Griffin beakers, 250 mL with 75 mm watch glasses and (optional) 75 mm
ribbed watch glasses.
6.10.5 (Optional) PTFE and/or quartz beakers, 250 mL with PTFE covers.
6.10.6 Evaporating dishes or high-form crucibles, porcelain, 100 mL capacity.
200.8-10
6.10.7 Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with
ETFE (ethylene tetrafluorethylene) screw closure, 125-250 mL capacities.
6.10.8 One-piece stem FEP wash bottle with screw closure, 125 mL capacity.
7.0
REAGENTS AND STANDARDS
7.1
Reagents may contain elemental impurities that might affect the integrity of
analytical data. Owing to the high sensitivity of ICP-MS, high-purity reagents
should be used whenever possible. All acids used for this method must be of
ultra high-purity grade. Suitable acids are available from a number of
manufacturers or may be prepared by sub-boiling distillation. Nitric acid is
preferred for ICP-MS in order to minimize polyatomic ion interferences. Several
polyatomic ion interferences result when hydrochloric acid is used (Table 2),
however, it should be noted that hydrochloric acid is required to maintain
stability in solutions containing antimony and silver. When hydrochloric acid is
used, corrections for the chloride polyatomic ion interferences must be applied to
all data.
7.1.1
Nitric acid, concentrated (sp.gr. 1.41).
7.1.2
Nitric acid (1+1) - Add 500 mL conc. nitric acid to 400 mL of regent grade
water and dilute to 1 L.
7.1.3
Nitric acid (1+9) - Add 100 mL conc. nitric acid to 400 mL of reagent
grade water and dilute to 1 L.
7.1.4
Hydrochloric acid, concentrated (sp.gr. 1.19).
7.1.5
Hydrochloric acid (1+1) - Add 500 mL conc. hydrochloric acid to 400 mL
of reagent grade water and dilute to 1 L.
7.1.6
Hydrochloric acid (1+4) - Add 200 mL conc. hydrochloric acid to 400 mL
of reagent grade water and dilute to 1 L.
7.1.7
Ammonium hydroxide, concentrated (sp.gr. 0.902).
7.1.8
Tartaric acid (CASRN 87-69-4).
7.2
Reagent water - All references to reagent grade water in this method refer to
ASTM Type I water (ASTM D1193).9 Suitable water may be prepared by passing
distilled water through a mixed bed of anion and cation exchange resins.
7.3
Standard Stock Solutions - Stock standards may be purchased from a reputable
commercial source or prepared from ultra high-purity grade chemicals or metals
(99.99-99.999% pure). All salts should be dried for one hour at 105°C, unless
otherwise specified. Stock solutions should be stored in FEP bottles. Replace
stock standards when succeeding dilutions for preparation of the multielement
stock standards can not be verified.
200.8-11
CAUTION:
Many metal salts are extremely toxic if inhaled or swallowed.
Wash hands thoroughly after handling.
The following procedures may be used for preparing standard stock solutions:
Note: Some metals, particularly those which form surface oxides require cleaning
prior to being weighed. This may be achieved by pickling the surface of the
metal in acid. An amount in excess of the desired weight should be pickled
repeatedly, rinsed with water, dried and weighed until the desired weight is
achieved.
7.3.1
Aluminum solution, stock 1 mL = 1000 µg Al: Pickle aluminum metal in
warm (1+1) HCl to an exact weight of 0.100 g. Dissolve in 10 mL conc.
HCl and 2 mL conc. nitric acid, heating to effect solution. Continue
heating until volume is reduced to 4 mL. Cool and add 4 mL reagent
grade water. Heat until the volume is reduced to 2 mL. Cool and dilute
to 100 mL with reagent grade water.
7.3.2
Antimony solution, stock 1 mL = 1000 µg Sb: Dissolve 0.100 g antimony
powder in 2 mL (1+1) nitric acid and 0.5 mL conc. hydrochloric acid,
heating to effect solution. Cool, add 20 mL reagent grade water and
0.15 g tartaric acid. Warm the solution to dissolve the white precipitate.
Cool and dilute to 100 mL with reagent grade water.
7.3.3
Arsenic solution, stock 1 mL = 1000 µg As: Dissolve 0.1320 g As 2O 3 in a
mixture of 50 mL reagent grade water and 1 mL conc. ammonium
hydroxide. Heat gently to dissolve. Cool and acidify the solution with
2 mL conc. nitric acid. Dilute to 100 mL with reagent grade water.
7.3.4
Barium solution, stock 1 mL = 1000 µg Ba: Dissolve 0.1437 g BaCO 3 in a
solution mixture of 10 mL reagent grade water and 2 mL conc. nitric acid.
Heat and stir to effect solution and degassing. Dilute to 100 mL with
reagent grade water.
7.3.5
Beryllium solution, stock 1 mL = 1000 µg Be: Dissolve 1.965 g
BeSO4C4H2O (DO NOT DRY) in 50 mL reagent grade water. Add 1 mL
conc. nitric acid. Dilute to 100 mL with reagent grade water.
7.3.6
Bismuth solution, stock 1 mL = 1000 µg Bi: Dissolve 0.1115 g Bi 2O 3 in
5 mL conc. nitric acid. Heat to effect solution. Cool and dilute to 100 mL
with reagent grade water.
7.3.7
Cadmium solution, stock 1 mL = 1000 µg Cd: Pickle cadmium metal in
(1+9) nitric acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1)
nitric acid, heating to effect solution. Cool and dilute to 100 mL with
reagent grade water.
7.3.8
Chromium solution, stock 1 mL = 1000 µg Cr: Dissolve 0.1923 g CrO3 in
a solution mixture of 10 mL reagent grade water and 1 mL conc. nitric
200.8-12
acid. Dilute to 100 mL with reagent grade water.
7.3.9
Cobalt solution, stock 1 mL = 1000 µg Co: Pickle cobalt metal in (1+9)
nitric acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1) nitric
acid, heating to effect solution. Cool and dilute to 100 mL with reagent
grade water.
7.3.10 Copper solution, stock 1 mL = 1000 µg Cu: Pickle copper metal in (1+9)
nitric acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1) nitric
acid, heating to effect solution. Cool and dilute to 100 mL with reagent
grade water.
7.3.11 Gold solution, stock 1 mL = 1000 µg Au: Dissolve 0.100 g high purity
(99.9999%) Au shot in 10 mL of hot conc. nitric acid by dropwise addition
of 5 mL conc. HCl and then reflux to expel oxides of nitrogen and
chlorine. Cool and dilute to 100 mL with reagent grade water.
7.3.12 Indium solution, stock 1 mL = 1000 µg In: Pickle indium metal in (1+1)
nitric acid to an exact weight of 0.100 g. Dissolve in 10 mL (1+1) nitric
acid, heating to effect solution. Cool and dilute to 100 mL with reagent
grade water.
7.3.13 Lead solution, stock 1 mL = 1000 µg Pb: Dissolve 0.1599 g PbNO3 in 5 mL
(1+1) nitric acid. Dilute to 100 mL with reagent grade water.
7.3.14 Magnesium solution, stock 1 mL = 1000 µg Mg: Dissolve 0.1658 g MgO
in 10 mL (1+1) nitric acid, heating to effect solution. Cool and dilute to
100 mL with reagent grade water.
7.3.15 Manganese solution, stock 1 mL = 1000 µg Mn: Pickle manganese flake
in (1+9) nitric acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1)
nitric acid, heating to effect solution. Cool and dilute to 100 mL with
reagent grade water.
7.3.16 Mercury solution, stock, 1 mL = 1000 µg Hg: DO NOT DRY. CAUTION:
highly toxic element. Dissolve 0.1354 g HgCl 2 in reagent water. Add
5.0 mL concentrated HNO3 and dilute to 100 mL with reagent water.
7.3.17 Molybdenum solution, stock 1 mL = 1000 µg Mo: Dissolve 0.1500 g MoO3
in a solution mixture of 10 mL reagent grade water and 1 mL conc.
ammonium hydroxide., heating to effect solution. Cool and dilute to
100 mL with reagent grade water.
7.3.18 Nickel solution, stock 1 mL = 1000 µg Ni: Dissolve 0.100 g nickel powder
in 5 mL conc. nitric acid, heating to effect solution. Cool and dilute to
100 mL with reagent grade water.
7.3.19 Scandium solution, stock 1 mL = 1000 µg Sc: Dissolve 0.1534 g Sc 2O 3 in
5 mL (1+1) nitric acid, heating to effect solution. Cool and dilute to
200.8-13
100 mL with reagent grade water.
7.3.20 Selenium solution, stock 1 mL = 1000 µg Se: Dissolve 0.1405 g SeO 2 in
20 mL ASTM Type I water. Dilute to 100 mL with reagent grade water.
7.3.21 Silver solution, stock 1 mL = 1000 µg Ag: Dissolve 0.100 g silver metal in
5 mL (1+1) nitric acid, heating to effect solution. Cool and dilute to
100 mL with reagent grade water. Store in dark container.
7.3.22 Terbium solution, stock 1 mL = 1000 µg Tb: Dissolve 0.1176 g Tb4O7 in
5 mL conc. nitric acid, heating to effect solution. Cool and dilute to
100 mL with reagent grade water.
7.3.23 Thallium solution, stock 1 mL = 1000 µg Tl: Dissolve 0.1303 g TlNO3 in
a solution mixture of 10 mL reagent grade water and 1 mL conc. nitric
acid. Dilute to 100 mL with reagent grade water.
7.3.24 Thorium solution, stock 1 mL = 1000 µg Th: Dissolve 0.2380 g
Th(NO3)4C4H2O (DO NOT DRY) in 20 mL reagent grade water. Dilute to
100 mL with reagent grade water.
7.3.25 Uranium solution, stock 1 mL = 1000 µg U: Dissolve 0.2110 g
UO2(NO3)2C6H2O (DO NOT DRY) in 20 mL reagent grade water and dilute
to 100 mL with reagent grade water.
7.3.26 Vanadium solution, stock 1 mL = 1000 µg V: Pickle vanadium metal in
(1+9) nitric acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1)
nitric acid, heating to effect solution. Cool and dilute to 100 mL with
reagent grade water.
7.3.27 Yttrium solution, stock 1 mL = 1000 µg Y: Dissolve 0.1270 g Y2O3 in 5 mL
(1+1) nitric acid, heating to effect solution. Cool and dilute to 100 mL
with reagent grade water.
7.3.28 Zinc solution, stock 1 mL = 1000 µg Zn: Pickle zinc metal in (1+9) nitric
acid to an exact weight of 0.100 g. Dissolve in 5 mL (1+1) nitric acid,
heating to effect solution. Cool and dilute to 100 mL with reagent grade
water.
7.4
Multielement Stock Standard Solutions - Care must be taken in the preparation
of multielement stock standards that the elements are compatible and stable.
Originating element stocks should be checked for the presence of impurities
which might influence the accuracy of the standard. Freshly prepared standards
should be transferred to acid cleaned, not previously used FEP fluorocarbon
bottles for storage and monitored periodically for stability. The following
combinations of elements are suggested:
200.8-14
Standard Solution A
Aluminum
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Standard Solution B
Mercury
Molybdenum
Nickel
Selenium
Thallium
Thorium
Uranium
Vanadium
Zinc
Barium
Silver
Except for selenium and mercury, multielement stock standard solutions A and
B (1 mL = 10 µg) may be prepared by diluting 1.0 mL of each single element
stock standard in the combination list to 100 mL with reagent water containing
1% (v/v) nitric acid. For mercury and selenium in solution A, aliquots of 0.05 mL
and 5.0 mL of the respective stock standards should be diluted to the specified
100 mL (1 ml = 0.5 µg Hg and 50 µg Se). Replace the multielement stock
standards when succeeding dilutions for preparation of the calibration standards
cannot be verified with the quality control sample.
7.4.1
7.5
Preparation of calibration standards - fresh multielement calibration
standards should be prepared every two weeks or as needed. Dilute each
of the stock multielement standard solutions A and B to levels appropriate
to the operating range of the instrument using reagent water containing
1% (v/v) nitric acid. The element concentrations in the standards should
be sufficiently high to produce good measurement precision and to
accurately define the slope of the response curve. Depending on the
sensitivity of the instrument, concentrations ranging from 10-200 µg/L are
suggested, except mercury, which should be limited to ≤5 µg/L. It should
be noted the selenium concentration is always a factor of 5 greater than
the other analytes. If the direct addition procedure is being used (Method
A, Section 10.3), add internal standards (Section 7.5) to the calibration
standards and store in FEP bottles. Calibration standards should be
verified initially using a quality control sample (Section 7.8).
Internal Standards Stock Solution - 1 mL = 100 µg. Dilute 10 mL of scandium,
yttrium, indium, terbium and bismuth stock standards (Section 7.3) to 100 mL
with reagent water, and store in a FEP bottle. Use this solution concentrate for
addition to blanks, calibration standards and samples, or dilute by an appropriate
amount using 1% (v/v) nitric acid, if the internal standards are being added by
peristaltic pump (Method B, Section 10.3).
Note: If mercury is to be determined by the "direct analysis" procedure, add an
aliquot of the gold stock standard (Section 7.3.11) to the internal standard solution
sufficient to provide a concentration of 100 µg/L in final the dilution of all blanks,
calibration standards, and samples.
200.8-15
7.6
Blanks - Three types of blanks are required for this method. A calibration blank
is used to establish the analytical calibration curve, the laboratory reagent blank
is used to assess possible contamination from the sample preparation procedure
and to assess spectral background and the rinse blank is used to flush the
instrument between samples in order to reduce memory interferences.
7.6.1
Calibration blank - Consists of 1% (v/v) nitric acid in reagent grade water.
If the direct addition procedure (Method A, Section 10.3) is being used,
add internal standards.
7.6.2
Laboratory reagent blank (LRB) - Must contain all the reagents in the same
volumes as used in processing the samples. The LRB must be carried
through the same entire preparation scheme as the samples including
digestion, when applicable. If the direct addition procedure (Method A,
Section 10.3) is being used, add internal standards to the solution after
preparation is complete.
7.6.3
Rinse blank - Consists of 2% (v/v) nitric acid in reagent grade water.
Note: If mercury is to be determined by the "direct analysis" procedure,
add gold (Section 7.3.11) to the rinse blank to a concentration of 100 µg/L.
7.7
Tuning Solution - This solution is used for instrument tuning and mass calibration
prior to analysis. The solution is prepared by mixing beryllium, magnesium,
cobalt, indium and lead stock solutions (Section 7.3) in 1% (v/v) nitric acid to
produce a concentration of 100 µg/L of each element. Internal standards are not
added to this solution. (Depending on the sensitivity of the instrument, this
solution may need to be diluted 10-fold.)
7.8
Quality Control Sample (QCS) - The QCS should be obtained from a source
outside the laboratory. The concentration of the QCS solution analyzed will
depend on the sensitivity of the instrument. To prepare the QCS dilute an
appropriate aliquot of analytes to a concentration ≤100 µg/L in 1% (v/v) nitric
acid. Because of lower sensitivity, selenium may be diluted to a concentration of
<500 µg/L, however, in all cases, mercury should be limited to a concentration
of ≤5 µg/L. If the direct addition procedure (Method A, Section 10.3) is being
used, add internal standards after dilution, mix and store in a FEP bottle. The
QCS should be analyzed as needed to meet data-quality needs and a fresh
solution should be prepared quarterly or more frequently as needed.
7.9
Laboratory Fortified Blank (LFB) - To an aliquot of LRB, add aliquots from
multielement stock standards A and B (Section 7.4) to prepared the LFB.
Depending on the sensitivity of the instrument, the fortified concentration used
should range from 40-100 µg/L for each analyte, except selenium and mercury.
For selenium the concentration should range from 200-500 µg/L, while the
concentration range mercury should be limited to 2-5 µg/L. The LFB must be
carried through the same entire preparation scheme as the samples including
sample digestion, when applicable. If the direct addition procedure (Method A,
Section 10.3) is being used, add internal standards to this solution after
200.8-16
preparation has been completed.
8.0
SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1
Prior to the collection of an aqueous sample, consideration should be given to the
type of data required, (i.e., dissolved or total recoverable), so that appropriate
preservation and pretreatment steps can be taken. The pH of all aqueous samples
must be tested immediately prior to aliquoting for processing or "direct analysis"
to ensure the sample has been properly preserved. If properly acid preserved, the
sample can be held up to 6 months before analysis.
8.2
For the determination of dissolved elements, the sample must be filtered through
a 0.45 µm pore diameter membrane filter at the time of collection or as soon
thereafter as practically possible. Use a portion of the sample to rinse the filter
flask, discard this portion and collect the required volume of filtrate. Acidify the
filtrate with (1+1) nitric acid immediately following filtration to pH <2.
8.3
For the determination of total recoverable elements in aqueous samples, samples
are not filtered, but acidified with (1+1) nitric acid to pH <2 (normally, 3 mL of
(1+1) acid per liter of sample is sufficient for most ambient and drinking water
samples). Preservation may be done at the time of collection, however, to avoid
the hazards of strong acids in the field, transport restrictions, and possible
contamination it is recommended that the samples be returned to the laboratory
within two weeks of collection and acid preserved upon receipt in the laboratory.
Following acidification, the sample should be mixed, held for 16 hours, and then
verified to be pH <2 just prior withdrawing an aliquot for processing or "direct
analysis". If for some reason such as high alkalinity the sample pH is verified to
be >2, more acid must be added and the sample held for 16 hours until verified
to be pH <2. See Section 8.1.
Note: When the nature of the sample is either unknown or known to be
hazardous, acidification should be done in a fume hood. See Section 5.2.
9.0
8.4
Solid samples require no preservation prior to analysis other than storage at 4°C.
There is no established holding time limitation for solid samples.
8.5
For aqueous samples, a field blank should be prepared and analyzed as required
by the data user. Use the same container and acid as used in sample collection.
QUALITY CONTROL
9.1
Each laboratory using this method is required to operate a formal quality control
(QC) program. The minimum requirements of this program consist of an initial
demonstration of laboratory capability, and the periodic analysis of laboratory
reagent blanks, fortified blanks and calibration solutions as a continuing check on
performance. The laboratory is required to maintain performance records that
define the quality of the data thus generated.
9.2
Initial Demonstration of Performance (mandatory)
200.8-17
9.2.1
The initial demonstration of performance is used to characterize
instrument performance (determination of linear calibration ranges and
analysis of quality control samples) and laboratory performance
(determination of method detection limits) prior to analyses conducted by
this method.
9.2.2
Linear calibration ranges - Linear calibration ranges are primarily detector
limited. The upper limit of the linear calibration range should be
established for each analyte by determining the signal responses from a
minimum of three different concentration standards, one of which is close
to the upper limit of the linear range. Care should be taken to avoid
potential damage to the detector during this process. The linear
calibration range which may be used for the analysis of samples should
be judged by the analyst from the resulting data. The upper LDR limit
should be an observed signal no more than 10% below the level
extrapolated from lower standards.
Determined sample analyte
concentrations that are greater than 90% of the determined upper LDR
limit must be diluted and reanalyzed. The LDRs should be verified
whenever, in the judgement of the analyst, a change in analytical
performance caused by either a change in instrument hardware or
operating conditions would dictate they be redetermined.
9.2.3
Quality control sample (QCS) - When beginning the use of this method,
on a quarterly basis or as required to meet data-quality needs, verify the
calibration standards and acceptable instrument performance with the
preparation and analyses of a QCS (Section 7.8). To verify the calibration
standards the determined mean concentration from three analyses of the
QCS must be within ±10% of the stated QCS value. If the QCS is used for
determining acceptable on-going instrument performance, analysis of the
QCS prepared to a concentration of 100 µg/L must be within ±10% of the
stated value or within the acceptance limits listed in Table 8, whichever
is the greater. (If the QCS is not within the required limits, an immediate
second analysis of the QCS is recommended to confirm unacceptable
performance.) If the calibration standards and/or acceptable instrument
performance cannot be verified, the source of the problem must be
identified and corrected before either proceeding on with the initial
determination of method detection limits or continuing with on-going
analyses.
9.2.4
Method detection limits (MDL) should be established for all analytes,
using reagent water (blank) fortified at a concentration of two to five times
the estimated detection limit.7 To determine MDL values, take seven
replicate aliquots of the fortified reagent water and process through the
entire analytical method. Perform all calculations defined in the method
and report the concentration values in the appropriate units. Calculate the
MDL as follows:
200.8-18
where:
t = Student's t value for a 99% confidence level and a standard
deviation estimate with n-1 degrees of freedom [t = 3.14 for
seven replicates]
S = standard deviation of the replicate analyses
Note: If additional confirmation is desired, reanalyze the seven replicate
aliquots on two more nonconsecutive days and again calculate the MDL
values for each day. An average of the three MDL values for each analyte
may provide for a more appropriate MDL estimate. If the relative
standard deviation (RSD) from the analyses of the seven aliquots is <10%,
the concentration used to determine the analyte MDL may have been
inappropriately high for the determination. If so, this could result in the
calculation of an unrealistically low MDL. Concurrently, determination
of MDL in reagent water represents a best case situation and does not
reflect possible matrix effects of real world samples. However, successful
analyses of LFMs (Section 9.4) can give confidence to the MDL value
determined in reagent water. Typical single laboratory MDL values using
this method are given in Table 7.
The MDLs must be sufficient to detect analytes at the required levels
according to compliance monitoring regulation (Section 1.2). MDLs
should be determined annually, when a new operator begins work or
whenever, in the judgement of the analyst, a change in analytical
performance caused by either a change in instrument hardware or
operating conditions would dictate they be redetermined.
9.3
Assessing Laboratory Performance (mandatory)
9.3.1
Laboratory reagent blank (LRB) - The laboratory must analyze at least one
LRB (Section 7.6.2) with each batch of 20 or fewer of samples of the same
matrix. LRB data are used to assess contamination from the laboratory
environment and to characterize spectral background from the reagents
used in sample processing. LRB values that exceed the MDL indicate
laboratory or reagent contamination should be suspected. When LRB
values constitute 10% or more of the analyte level determined for a sample
or is 2.2 times the analyte MDL whichever is greater, fresh aliquots of the
samples must be prepared and analyzed again for the affected analytes
after the source of contamination has been corrected and acceptable LRB
values have been obtained.
9.3.2
Laboratory fortified blank (LFB) - The laboratory must analyze at least one
LFB (Section 7.9) with each batch of samples. Calculate accuracy as
percent recovery using the following equation:
200.8-19
where:
R
LFB
LRB
s
=
=
=
=
percent recovery
laboratory fortified blank
laboratory reagent blank
concentration equivalent of analyte added to fortify the
LBR solution
If the recovery of any analyte falls outside the required control limits of
85-115%, that analyte is judged out of control, and the source of the
problem should be identified and resolved before continuing analyses.
9.3.3
The laboratory must use LFB analyses data to assess laboratory
performance against the required control limits of 85-115% (Section 9.3.2).
When sufficient internal performance data become available (usually a
minimum of 20-30 analyses), optional control limits can be developed from
the mean percent recovery (x) and the standard deviation (S) of the mean
percent recovery. These data can be used to establish the upper and lower
control limits as follows:
UPPER CONTROL LIMIT = x + 3S
LOWER CONTROL LIMIT = x - 3S
The optional control limits must be equal to or better than the required
control limits of 85-115%.
After each five to ten new recovery
measurements, new control limits can be calculated using only the most
recent 20-30 data points. Also, the standard deviation (S) data should be
used to establish an on-going precision statement for the level of
concentrations included in the LFB. These data must be kept on file and
be available for review.
9.3.4
9.4
Instrument performance - For all determinations the laboratory must check
instrument performance and verify that the instrument is properly
calibrated on a continuing basis. To verify calibration run the calibration
blank and calibration standards as surrogate samples immediately
following each calibration routine, after every ten analyses and at the end
of the sample run. The results of the analyses of the standards will
indicate whether the calibration remains valid. The analysis of all analytes
within the standard solutions must be within ±10% of calibration. If the
calibration cannot be verified within the specified limits, the instrument
must be recalibrated. (The instrument responses from the calibration
check may be used for recalibration purposes, however, it must be verified
before continuing sample analysis.) If the continuing calibration check is
not confirmed within ±15%, the previous 10 samples must be reanalyzed
after recalibration. If the sample matrix is responsible for the calibration
drift, it is recommended that the previous 10 samples are reanalyzed in
groups of five between calibration checks to prevent a similar drift
situation from occurring.
Assessing Analyte Recovery and Data Quality
200.8-20
9.4.1
Sample homogeneity and the chemical nature of the sample matrix can
affect analyte recovery and the quality of the data. Taking separate
aliquots from the sample for replicate and fortified analyses can in some
cases assess the effect. Unless otherwise specified by the data user,
laboratory or program, the following laboratory fortified matrix (LFM)
procedure (Section 9.4.2) is required.
9.4.2
The laboratory must add a known amount of analyte to a minimum of
10% of the routine samples. In each case the LFM aliquot must be a
duplicate of the aliquot used for sample analysis and for total recoverable
determinations added prior to sample preparation. For water samples, the
added analyte concentration must be the same as that used in the
laboratory fortified blank (Section 7.9).
For solid samples, the
concentration added should be 100 mg/kg equivalent (200 µg/L in the
analysis solution) except silver which should be limited to 50 mg/kg
(Section 1.8). Over time, samples from all routine sample sources should
be fortified.
9.4.3
Calculate the percent recovery for each analyte, corrected for background
concentrations measured in the unfortified sample, and compare these
values to the designated LFM recovery range of 70-130%. Recovery
calculations are not required if the concentration of the analyte added is
less than 30% of the sample background concentration. Percent recovery
may be calculated in units appropriate to the matrix, using the following
equation:
where:
R
Cs
C
s
= percent recovery
= fortified sample concentration
=
sample background concentration
= concentration equivalent of analyte added to fortify the
sample
9.4.4
If recovery of any analyte falls outside the designated range and
laboratory performance for that analyte is shown to be in control
(Section 9.3), the recovery problem encountered with the fortified sample
is judged to be matrix related, not system related. The data user should
be informed that the result for that analyte in the unfortified sample is
suspect due to either the heterogeneous nature of the sample or an
uncorrected matrix effect.
9.4.5
Internal standards responses - The analyst is expected to monitor the
responses from the internal standards throughout the sample set being
200.8-21
analyzed. Ratios of the internal standards responses against each other
should also be monitored routinely. This information may be used to
detect potential problems caused by mass dependent drift, errors incurred
in adding the internal standards or increases in the concentrations of
individual internal standards caused by background contributions from
the sample. The absolute response of any one internal standard must not
deviate more than 60-125% of the original response in the calibration
blank. If deviations greater than these are observed, flush the instrument
with the rinse blank and monitor the responses in the calibration blank.
If the responses of the internal standards are now within the limit, take a
fresh aliquot of the sample, dilute by a further factor of two, add the
internal standards and reanalyze. If after flushing the response of the
internal standards in the calibration blank are out of limits, terminate the
analysis and determine the cause of the drift. Possible causes of drift may
be a partially blocked sampling cone or a change in the tuning condition
of the instrument.
10.0
CALIBRATION AND STANDARDIZATION
10.1
Operating conditions - Because of the diversity of instrument hardware, no
detailed instrument operating conditions are provided. The analyst is advised to
follow the recommended operating conditions provided by the manufacturer. It
is the responsibility of the analyst to verify that the instrument configuration and
operating conditions satisfy the analytical requirements and to maintain quality
control data verifying instrument performance and analytical results. Instrument
operating conditions which were used to generate precision and recovery data for
this method (Section 13.0) are included in Table 6.
10.2
Precalibration routine - The following precalibration routine must be completed
prior to calibrating the instrument until such time it can be documented with
periodic performance data that the instrument meets the criteria listed below
without daily tuning.
10.2.1 Initiate proper operating configuration of instrument and data system.
Allow a period of not less than 30 minutes for the instrument to warm up.
During this process conduct mass calibration and resolution checks using
the tuning solution. Resolution at low mass is indicated by magnesium
isotopes 24, 25, and 26. Resolution at high mass is indicated by lead
isotopes 206, 207, and 208. For good performance adjust spectrometer
resolution to produce a peak width of approximately 0.75 amu at 5% peak
height. Adjust mass calibration if it has shifted by more than 0.1 amu
from unit mass.
10.2.2 Instrument stability must be demonstrated by running the tuning solution
(Section 7.7) a minimum of five times with resulting relative standard
deviations of absolute signals for all analytes of less than 5%.
10.3
Internal Standardization - Internal standardization must be used in all analyses
to correct for instrument drift and physical interferences. A list of acceptable
200.8-22
internal standards is provided in Table 3. For full mass range scans, a minimum
of three internal standards must be used. Procedures described in this method
for general application, detail the use of five internal standards; scandium,
yttrium, indium, terbium and bismuth. These were used to generate the precision
and recovery data attached to this method. Internal standards must be present
in all samples, standards and blanks at identical levels. This may be achieved by
directly adding an aliquot of the internal standards to the CAL standard, blank
or sample solution (Method A, Section 10.3), or alternatively by mixing with the
solution prior to nebulization using a second channel of the peristaltic pump and
a mixing coil (Method B, Section 10.3). The concentration of the internal standard
should be sufficiently high that good precision is obtained in the measurement
of the isotope used for data correction and to minimize the possibility of
correction errors if the internal standard is naturally present in the sample.
Depending on the sensitivity of the instrument, a concentration range of 20-200
µg/L of each internal standard is recommended. Internal standards should be
added to blanks, samples and standards in a like manner, so that dilution effects
resulting from the addition may be disregarded.
11.0
10.4
Calibration - Prior to initial calibration, set up proper instrument software
routines for quantitative analysis. The instrument must be calibrated using one
of the internal standard routines (Method A or B) described in Section 10.3. The
instrument must be calibrated for the analytes to be determined using the
calibration blank (Section 7.6.1) and calibration standards A and B (Section 7.4.1)
prepared at one or more concentration levels. A minimum of three replicate
integrations are required for data acquisition. Use the average of the integrations
for instrument calibration and data reporting.
10.5
The rinse blank should be used to flush the system between solution changes for
blanks, standards and samples. Allow sufficient rinse time to remove traces of
the previous sample (Section 4.1.5). Solutions should be aspirated for 30 seconds
prior to the acquisition of data to allow equilibrium to be established.
PROCEDURE
11.1
Aqueous Sample Preparation - Dissolved Analytes
11.1.1 For the determination of dissolved analytes in ground and surface waters,
pipet an aliquot (≥20 mL) of the filtered, acid preserved sample into a
50 mL polypropylene centrifuge tube. Add an appropriate volume of
(1+1) nitric acid to adjust the acid concentration of the aliquot to
approximate a 1% (v/v) nitric acid solution (e.g., add 0.4 mL (1+1) HNO3
to a 20 mL aliquot of sample). If the direct addition procedure
(Method A, Section 10.3) is being used, add internal standards, cap the
tube and mix. The sample is now ready for analysis (Section 1.2).
Allowance for sample dilution should be made in the calculations.
Note: If a precipitate is formed during acidification, transport, or storage,
the sample aliquot must be treated using the procedure in Section 11.2
prior to analysis.
200.8-23
11.2
Aqueous Sample Preparation - Total Recoverable Analytes
11.2.1 For the "direct analysis" of total recoverable analytes in drinking water
samples containing turbidity <1 NTU, treat an unfiltered acid preserved
sample aliquot using the sample preparation procedure described in
Section 11.1.1 while making allowance for sample dilution in the data
calculation. For the determination of total recoverable analytes in all other
aqueous samples or for preconcentrating drinking water samples prior to
analysis follow the procedure given in Sections 11.2.2 through 11.2.8.
11.2.2 For the determination of total recoverable analytes in aqueous samples
(other than drinking water with <1 NTU turbidity), transfer a 100 mL
(±1 mL) aliquot from a well mixed, acid preserved sample to a 250 mL
Griffin beaker (Sections 1.2, 1.3, 1.7, and 1.8). (When necessary, smaller
sample aliquot volumes may be used.)
Note: If the sample contains undissolved solids >1%, a well mixed, acid
preserved aliquot containing no more than 1 g particulate material should
be cautiously evaporated to near 10 mL and extracted using the acidmixture procedure described in Sections 11.3.3 through 11.3.7.
11.2.3 Add 2 mL (1+1) nitric acid and 1.0 mL of (1+1) hydrochloric acid to the
beaker containing the measured volume of sample. Place the beaker on
the hot plate for solution evaporation. The hot plate should be located in
a fume hood and previously adjusted to provide evaporation at a
temperature of approximately but no higher than 85°C. (See the following
note.) The beaker should be covered with an elevated watch glass or
other necessary steps should be taken to prevent sample contamination
from the fume hood environment.
Note: For proper heating adjust the temperature control of the hot plate
such that an uncovered Griffin beaker containing 50 mL of water placed
in the center of the hot plate can be maintained at a temperature
approximately but no higher than 85°C. (Once the beaker is covered with
a watch glass the temperature of the water will rise to approximately
95°C.)
11.2.4 Reduce the volume of the sample aliquot to about 20 mL by gentle heating
at 85°C. DO NOT BOIL. This step takes about two hours for a 100 mL
aliquot with the rate of evaporation rapidly increasing as the sample
volume approaches 20 mL. (A spare beaker containing 20 mL of water
can be used as a gauge.)
11.2.5 Cover the lip of the beaker with a watch glass to reduce additional
evaporation and gently reflux the sample for 30 minutes. (Slight boiling
may occur, but vigorous boiling must be avoided to prevent loss of the
HCl-H2O azeotrope.)
11.2.6 Allow the beaker to cool. Quantitatively transfer the sample solution to
200.8-24
a 50 mL volumetric flask or 50 mL class A stoppered graduated cylinder,
make to volume with reagent water, stopper and mix.
11.2.7 Allow any undissolved material to settle overnight, or centrifuge a portion
of the prepared sample until clear. (If after centrifuging or standing
overnight the sample contains suspended solids that would clog the
nebulizer, a portion of the sample may be filtered for their removal prior
to analysis. However, care should be exercised to avoid potential
contamination from filtration.)
11.2.8 Prior to analysis, adjust the chloride concentration by pipetting 20 mL of
the prepared solution into a 50 mL volumetric flask, dilute to volume with
reagent water and mix. (If the dissolved solids in this solution are >0.2%,
additional dilution may be required to prevent clogging of the extraction
and/or skimmer cones. If the direct addition procedure (Method A,
Section 10.3) is being used, add internal standards and mix. The sample
is now ready for analysis. Because the effects of various matrices on the
stability of diluted samples cannot be characterized, all analyses should be
performed as soon as possible after the completed preparation.
11.3
Solid Sample Preparation - Total Recoverable Analytes
11.3.1 For the determination of total recoverable analytes in solid samples, mix
the sample thoroughly and transfer a portion (>20 g) to tared weighing
dish, weigh the sample and record the wet weight (WW). (For samples
with <35% moisture a 20 g portion is sufficient. For samples with
moisture >35% a larger aliquot 50-100 g is required.) Dry the sample to
a constant weight at 60°C and record the dry weight (DW) for calculation
of percent solids (Section 12.6). (The sample is dried at 60°C to prevent
the loss of mercury and other possible volatile metallic compounds, to
facilitate sieving, and to ready the sample for grinding.)
11.3.2 To achieve homogeneity, sieve the dried sample using a 5-mesh
polypropylene sieve and grind in a mortar and pestle. (The sieve, mortar
and pestle should be cleaned between samples.) From the dried, ground
material weigh accurately a representative 1.0 ± 0.01 g aliquot (W) of the
sample and transfer to a 250 mL Phillips beaker for acid extraction.
11.3.3 To the beaker add 4 mL of (1+1) HNO 3 and 10 mL of (1+4) HCl. Cover
the lip of the beaker with a watch glass. Place the beaker on a hot plate
for reflux extraction of the analytes. The hot plate should be located in a
fume hood and previously adjusted to provide a reflux temperature of
approximately 95°C. (See the following note.)
Note: For proper heating adjust the temperature control of the hot plate
such that an uncovered Griffin beaker containing 50 mL of water placed
in the center of the hot plate can be maintained at a temperature
approximately but no higher than 85°C. (Once the beaker is covered with
a watch glass the temperature of the water will rise to approximately
200.8-25
95°C.) Also, a block digester capable of maintaining a temperature of
95°C and equipped with 250 mL constricted volumetric digestion tubes
may be substituted for the hot plate and conical beakers in the extraction
step.
11.3.4 Heat the sample and gently reflux for 30 minutes. Very slight boiling may
occur, however vigorous boiling must be avoided to prevent loss of the
HCl-H2O azeotrope. Some solution evaporation will occur (3-4 mL).
11.3.5 Allow the sample to cool and quantitatively transfer the extract to a
100 mL volumetric flask. Dilute to volume with reagent water, stopper
and mix.
11.3.6 Allow the sample extract solution to stand overnight to separate insoluble
material or centrifuge a portion of the sample solution until clear. (If after
centrifuging or standing overnight the extract solution contains suspended
solids that would clog the nebulizer, a portion of the extract solution may
be filtered for their removal prior to analysis. However, care should be
exercised to avoid potential contamination from filtration.)
11.3.7 Prior to analysis, adjust the chloride concentration by pipetting 20 mL of
the prepared solution into a 100 mL volumetric flask, dilute to volume
with reagent water and mix. (If the dissolved solids in this solution are
>0.2%, additional dilution may be required to prevent clogging of the
extraction and/or skimmer cones. If the direct addition procedure
(Method A, Section 10.3) is being used, add internal standards and mix.
The sample extract is now ready for analysis. Because the effects of
various matrices on the stability of diluted samples cannot be
characterized, all analyses should be performed as soon as possible after
the completed preparation.
Note: Determine the percent solids in the sample for use in calculations
and for reporting data on a dry weight basis.
11.4
Sample Analysis
11.4.1 For every new or unusual matrix, it is highly recommended that a semiquantitative analysis be carried out to screen the sample for elements at
high concentration. Information gained from this may be used to prevent
potential damage to the detector during sample analysis and to identify
elements which may be higher than the linear range. Matrix screening
may be carried out by using intelligent software, if available, or by
diluting the sample by a factor of 500 and analyzing in a semi-quantitative
mode. The sample should also be screened for background levels of all
elements chosen for use as internal standards in order to prevent bias in
the calculation of the analytical data.
11.4.2 Initiate instrument operating configuration. Tune and calibrate the
instrument for the analytes of interest (Section 10.0).
200.8-26
11.4.3 Establish instrument software run procedures for quantitative analysis.
For all sample analyses, a minimum of three replicate integrations are
required for data acquisition. Use the average of the integrations for data
reporting.
11.4.4 All masses which might affect data quality must be monitored during the
analytical run. As a minimum, those masses prescribed in Table 4 must
be monitored in the same scan as is used for the collection of the data.
This information should be used to correct the data for identified
interferences.
11.4.5 During the analysis of samples, the laboratory must comply with the
required quality control described in Sections 9.3 and 9.4. Only for the
determination of dissolved analytes or the "direct analysis" of drinking
water with turbidity of <1 NTU is the sample digestion step of the LRB,
LFB, and LFM not required.
11.4.6 The rinse blank should be used to flush the system between samples.
Allow sufficient time to remove traces of the previous sample or a
minimum of one minute (Section 4.1.5). Samples should be aspirated for
30 seconds prior to the collection of data.
11.4.7 Samples having concentrations higher than the established linear dynamic
range should be diluted into range and reanalyzed. The sample should
first be analyzed for the trace elements in the sample, protecting the
detector from the high concentration elements, if necessary, by the
selection of appropriate scanning windows. The sample should then be
diluted for the determination of the remaining elements. Alternatively,
the dynamic range may be adjusted by selecting an alternative isotope of
lower natural abundance, provided quality control data for that isotope
have been established. The dynamic range must not be adjusted by
altering instrument conditions to an uncharacterized state.
12.0
DATA ANALYSIS AND CALCULATIONS
12.1
Elemental equations recommended for sample data calculations are listed in Table
5. Sample data should be reported in units of µg/L for aqueous samples or
mg/kg dry weight for solid samples. Do not report element concentrations below
the determined MDL.
12.2
For data values less than 10, two significant figures should be used for reporting
element concentrations. For data values greater than or equal to 10, three
significant figures should be used.
12.3
For aqueous samples prepared by total recoverable procedure (Section 11.2),
multiply solution concentrations by the dilution factor 1.25. If additional dilutions
were made to any samples or an aqueous sample was prepared using the acidmixture procedure described in Section 11.3, the appropriate factor should be
applied to the calculated sample concentrations.
200.8-27
12.4
For total recoverable analytes in solid samples (Section 11.3), round the solution
analyte concentrations (µg/L in the analysis solution) as instructed in Section 12.2.
Multiply the µ/L concentrations in the analysis solution by the factor 0.005 to
calculate the mg/L analyte concentration in the 100 mL extract solution. (If
additional dilutions were made to any samples, the appropriate factor should be
applied to calculate analyte concentrations in the extract solution.) Report the
data up to three significant figures as mg/kg dry-weight basis unless specified
otherwise by the program or data user. Calculate the concentration using the
equation below:
where:
C =
V =
W=
Concentration in the extract (mg/L)
Volume of extract (L, 100 mL = 0.1L)
Weight of sample aliquot extracted (g x 0.001 = kg)
Do not report analyte data below the estimated solids MDL or an adjusted MDL
because of additional dilutions required to complete the analysis.
12.5
To report percent solids in solid samples (Sect. 11.3) calculate as follows:
where:
DW =
Sample weight (g) dried at 60oC
WW = Sample weight (g) before drying
Note: If the data user, program or laboratory requires that the reported percent
solids be determined by drying at 105°C, repeat the procedure given in
Section 11.3 using a separate portion (>20 g) of the sample and dry to constant
weight at 103-105°C.
12.6
Data values should be corrected for instrument drift or sample matrix induced
interferences by the application of internal standardization. Corrections for
characterized spectral interferences should be applied to the data. Chloride
interference corrections should be made on all samples, regardless of the addition
of hydrochloric acid, as the chloride ion is a common constituent of
environmental samples.
12.7
If an element has more than one monitored isotope, examination of the
concentration calculated for each isotope, or the isotope ratios, will provide useful
information for the analyst in detecting a possible spectral interference.
200.8-28
Consideration should therefore be given to both primary and secondary isotopes
in the evaluation of the element concentration. In some cases, secondary isotopes
may be less sensitive or more prone to interferences than the primary
recommended isotopes, therefore differences between the results do not
necessarily indicate a problem with data calculated for the primary isotopes.
12.8
13.0
The QC data obtained during the analyses provide an indication of the quality of
the sample data and should be provided with the sample results.
METHOD PERFORMANCE
13.1
Instrument operating conditions used for single laboratory testing of the method
are summarized in Table 6. Total recoverable digestion and "direct analysis"
MDLs determined using the procedure described in Section 9.2.4, are listed in
Table 7.
13.2
Data obtained from single laboratory testing of the method are summarized in
Table 9 for five water samples representing drinking water, surface water, ground
water and waste effluent. Samples were prepared using the procedure described
in Section 11.2. For each matrix, five replicates were analyzed and the average
of the replicates used for determining the sample background concentration for
each element. Two further pairs of duplicates were fortified at different
concentration levels. For each method element, the sample background
concentration, mean percent recovery, the standard deviation of the percent
recovery and the relative percent difference between the duplicate fortified
samples are listed in Table 8.
13.3
Data obtained from single laboratory testing of the method are summarized in
Table 10 for three solid samples consisting of SRM 1645 River Sediment, EPA
Hazardous Soil and EPA Electroplating Sludge. Samples were prepared using the
procedure described in Section 11.3. For each method element, the sample
background concentration, mean percent recovery, the standard deviation of the
percent recovery and the relative percent difference between the duplicate
fortified samples were determined as for Section 13.2.
13.4
Data obtained from single laboratory testing of the method for drinking water
analysis using the "direct analysis" procedure (Section 11.2.1) are given in
Table 11. Three drinking water samples of varying hardness collected from
Regions 4, 6, and 10 were fortified to contain 1 µg/L of all metal primary
contaminants, except selenium, which was added to a concentration of 20 µg/L.
For each matrix, four replicate aliquots were analyzed to determine the sample
background concentration of each analyte and four fortified aliquots were
analyzed to determine mean percent recovery in each matrix. Listed in the
Table 11 are the average mean percent recovery of each analyte in the three
matrices and the standard deviation of the mean percent recoveries.
13.5
Listed in Table 12 are the regression equations for precision and bias developed
from the joint USEPA/Association of Official Analytical Chemists (AOAC)
multilaboratory validation study conducted on this method. These equations
200.8-29
were developed from data received from 13 laboratories on reagent water,
drinking water and ground water. Listed in Tables 13 and 14, respectively, are
the precision and recovery data from a wastewater digestate supplied to all
laboratories and from a wastewater of the participant's choice. For a complete
review of the study see Reference 11, Section 16.0 of this method.
14.0
15.0
POLLUTION PREVENTION
14.1
Pollution prevention encompasses any technique that reduces or eliminates the
quantity or toxicity of waste at the point of generation. Numerous opportunities
for pollution prevention exist in laboratory operation. The EPA has established
a preferred hierarchy of environmental management techniques that places
pollution prevention as the management option of first choice. Whenever
feasible, laboratory personnel should use pollution prevention techniques to
address their waste generation. When wastes cannot be feasibly reduced at the
source, the Agency recommends recycling as the next best option.
14.2
For information about pollution prevention that may be applicable to laboratories
and research institutions, consult “Less is Better:
Laboratory Chemical
Management for Waste Reduction”, available from the American Chemical
Society's Department of Government Relations and Science Policy, 1155 16th
Street N.W., Washington D.C. 20036, (202)872-4477.
WASTE MANAGEMENT
15.1
16.0
The Environmental Protection Agency requires that laboratory waste management
practices be conducted consistent with all applicable rules and regulations. The
Agency urges laboratories to protect the air, water, and land by minimizing and
controlling all releases from hoods and bench operations, complying with the
letter and spirit of any sewer discharge permits and regulations, and by
complying with all solid and hazardous waste regulations, particularly the
hazardous waste identification rules and land disposal restrictions. For further
information on waste management consult “The Waste Management Manual for
Laboratory Personnel”, available from the American Chemical Society at the
address listed in the Section 14.2.
REFERENCES
1.
Gray, A.L. and A. R. Date. Inductively Coupled Plasma Source Mass
Spectrometry Using Continuum Flow Ion Extraction. Analyst 108 1033-1050, 1983.
2.
Houk, R.S. et al. Inductively Coupled Argon Plasma as an Ion Source for Mass
Spectrometric Determination of Trace Elements. Anal Chem. 52 2283-2289, 1980.
3.
Houk, R.S. Mass Spectrometry of Inductively Coupled Plasmas. Anal. Chem. 58
97A-105A, 1986.
4.
Thompson, J.J. and R. S. Houk. A Study of Internal Standardization in
Inductively Coupled Plasma-Mass Spectrometry. Appl. Spec. 41 801-806, 1987.
200.8-30
5.
Carcinogens - Working With Carcinogens, Department of Health, Education, and
Welfare, Public Health Service, Center for Disease Control, National Institute for
Occupational Safety and Health, Publication No. 77-206, Aug. 1977. Available
from the National Technical Information Service (NTIS) as PB-277256.
6.
OSHA Safety and Health Standards, General Industry, (29 CFR 1910),
Occupational Safety and Health Administration, OSHA 2206, (Revised,
January 1976).
7.
Safety in Academic Chemistry Laboratories, American Chemical Society
Publication, Committee on Chemical Safety, 3rd Edition, 1979.
8.
Proposed OSHA Safety and Health Standards, Laboratories, Occupational Safety
and Health Administration, Federal Register, July 24, 1986.
9.
American Society for Testing and Materials. Standard Specification for Reagent
Water, D1193-77. Annual Book of ASTM Standards, Vol. 11.01. Philadelphia, PA,
1991.
10.
Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.
11.
Longbottom, J.E. et. al. Determination of Trace Elements in Water by Inductively
Coupled Plasma-Mass Spectrometry: Collaborative Study, Journal of AOAC
International 77 1004-1023, 1994.
12.
Hinners, T.A. Interferences in ICP-MS by Bromine Species. Winter Conference
on Plasma Spectrochemistry, San Diego, CA, January, 10-15, 1994.
200.8-31
17.0
TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA
TABLE 1: ESTIMATED INSTRUMENT DETECTION LIMITS
Element
Aluminum
Antimony
Arsenic(3)
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium(3)
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
Recommended
Analytical Mass
27
123
75
137
9
111
52
59
63
206, 207, 208
55
202
98
60
82
107
205
232
238
51
66
Scanning
Mode1
0.05
0.08
0.9
0.5
0.1
0.1
0.07
0.03
0.03
0.08
0.1
n.a
0.1
0.2
5
0.05
0.09
0.03
0.02
0.02
0.2
Selection Ion
Monitoring Mode2,3
0.02
0.008
0.02
0.03
0.02
0.02
0.04
0.002
0.004
0.015
0.007
0.2
0.005
0.07
1.3
0.004
0.014
0.005
0.005
0.006
0.07
Instrument detection limits (3F) estimated from seven replicate integrations of the
blank (1% v/v nitric acid) following calibration of the instrument with three replicate
integrations of a multi-element standard.
1
Instrument operating conditions and data acquisition mode are given in Table 6.
2
IDLs determined using state-of-the-art instrumentation (1994). Data for75 As,77 Se,
and 82Se were acquired using a dwell time of 4.096 seconds with 1500 area count per
sec 83Kr present in argon supply. All other data were acquired using a dwell time of
1.024 seconds per AMU monitored.
200.8-32
TABLE 2: COMMON MOLECULAR ION INTERFERENCES IN ICP-MS
BACKGROUND MOLECULAR IONS
Molecular Ion
NH+
OH+
OH2+
C2+
CN+
CO+
N2+
N2H+
NO+
NOH+
O2+
O2H+
36
ArH+
38
ArH+
40
ArH+
CO2+
CO2H+
ArC+, ArO+
ArN+
ArNH+
ArO+
ArOH+
40
Ar36Ar+
40
Ar38Ar+
40
Ar+
Mass
15
17
18
24
26
28
28
29
30
31
32
33
37
39
41
44
45
52
54
55
56
57
76
78
80
a
Element Interferencea
Sc
Cr
Cr
Mn
Se
Se
Se
method elements or internal standards affected by the molecular ions.
200.8-33
TABLE 2: COMMON MOLECULAR ION INTERFERENCES IN ICP-MS (Cont’d)
MATRIX MOLECULAR IONS
Molecular Ion
Mass
Element Interferencea
Bromide12
81
BrH +
BrO+
81
BrO+
81
BrOH+
82
95
97
98
Se
Mo
Mo
Mo
Ar81Br+
121
Sb
35
ClO+
ClOH+
37
ClO+
37
ClOH+
51
52
53
54
V
Cr
Cr
Cr
Ar35Cl+
Ar37Cl+
75
77
As
Se
32
SO+
SOH+
34
SO+
34
SOH+
SO2+, S2+
48
49
50
51
64
V, Cr
V
Zn
Ar32S+
Ar34S+
72
74
PO+
POH+
PO2+
47
48
63
ArP+
71
79
Chloride
35
Sulphate
32
Phosphate
Group I, II Metals
ArNa+
ArK+
ArCa+
63
79
80
200.8-34
Cu
Cu
TABLE 2: COMMON MOLECULAR ION INTERFERENCES IN ICP-MS (Cont’d)
MATRIX MOLECULAR IONS
Molecular Ion
Matrix Oxides*
TiO
ZrO
MoO
Mass
Element Interferencea
62-66
106-112
108-116
Ni, Cu, Zn
Ag, Cd
Cd
*
Oxide interferences will normally be very small and will only impact the method
elements when present at relatively high concentrations. Some examples of matrix
oxides are listed of which the analyst should be aware. It is recommended that Ti
and Zr isotopes are monitored in solid waste samples, which are likely to contain
high levels of these elements. Mo is monitored as a method analyte.
200.8-35
TABLE 3: INTERNAL STANDARDS AND LIMITATIONS OF USE
Internal Standard
6
Lithium
Scandium
Yttrium
Rhodium
Indium
Terbium
Holmium
Lutetium
Bismuth
Mass
6
45
89
103
115
159
165
175
209
Possible Limitation
a
polyatomic ion interference
a,b
isobaric interference by Sn
a
a May be present in environmental samples.
b In some instruments Yttrium may form measurable amounts of YO + (105 amu)and
YOH+ (106 amu). If this is the case, care should be taken in the use of the cadmium
elemental correction equation.
Internal standards recommended for use with this method are shown in bold face.
Preparation procedures for these are included in Section 7.3.
200.8-36
TABLE 4: RECOMMENDED ANALYTICAL ISOTOPES AND ADDITIONAL
MASSES WHICH MUST BE MONITORED
Isotope
Element of Interest
27
121, 123
75
135, 137
9
106, 108, 111, 114
52, 53
59
63, 65
206, 207, 208
55
95, 97, 98
60, 62
77, 82
107, 109
203, 205
232
238
51
66, 67, 68
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
83
99
105
118
Krypton
Ruthenium
Palladium
Tin
NOTE: Isotopes recommended for analytical determination are underlined.
200.8-37
TABLE 5: RECOMMENDED ELEMENTAL EQUATIONS FOR DATA
CALCULATIONS
Element
Elemental Equation
Note
Al
(1.000) (27C)
Sb
(1.000) (123C)
As
(1.000) (75C)-(3.127) [(77 C)-(0.815) (82 C)]
Ba
(1.000) (137C)
Be
(1.000) (9C)
Cd
(1.000) (111C)-(1.073) [(108 C)-(0.712) (106 C)]
(2)
Cr
(1.000) (52C)
(3)
Co
(1.000) (59C)
Cu
(1.000) (63C)
Pb
(1.000) (206C)+(1.000) [(207 C)+(1.000) (208 C)]
Mn
(1.000) (55C)
Mo
(1.000) (98C)-(0.146) (99 C)
Ni
(1.000) (60C)
Se
(1.000) (82C)
Ag
(1.000) (107C)
Tl
(1.000) (205C)
Th
(1.000) (232C)
U
(1.000) (238C)
V
(1.000) (51C)-(3.127) [(53 C)-(0.113) (52 C)]
Zn
(1.000) (66C)
(1)
(4)
(5)
(6)
200.8-38
(7)
TABLE 5: RECOMMENDED ELEMENTAL EQUATIONS FOR DATA
CALCULATIONS
Element
Elemental Equation
Bi
(1.000) (209C)
In
(1.000) (209C)-(0.016) (118C)
Sc
(1.000) (45C)
Tb
(1.000) (159C)
Y
(1.000) (89C)
Note
(8)
C - Calibration blank subtracted counts at specified mass.
(1) - Correction for chloride interference with adjustment for 77Se. ArCl 75/77 ratio
may be determined from the reagent blank. Isobaric mass 82 must be from Se only
and not BrH+.
(2) - Correction for MoO interference. Isobaric mass 106 must be from Cd only not
ZrO+. An additional isobaric elemental correction should be made if palladium is
present.
(3) - In 0.4% v/v HCl, the background from ClOH will normally be small. However
the contribution may be estimated from the reagent blank. Isobaric mass must be
from Cr only not ArC+.
(4) - Allowance for isotopic variability of lead isotopes.
(5) - Isobaric elemental correction for ruthenium.
(6) - Some argon supplies contain krypton as an impurity. Selenium is corrected for
82
Kr by background subtraction.
(7) - Correction for chloride interference with adjustment for 53Cr. ClO 51/53 ratio
may be determined from the reagent blank. Isobaric mass 52 must be from Cr only
not ArC+.
(8) - Isobaric elemental correction for tin.
200.8-39
TABLE 6: INSTRUMENT OPERATING CONDITIONS FOR PRECISION
AND RECOVERY DATA1
Instrument
Plasma foward power
Coolant flow rate
Auxillary flow rate
Nebulizer flow rate
Solution uptake rate
Spray chamber temperature
VG PlasmaQuad Type I
1.35 kW
13.5 L/min.
0.6 L/min.
0.78 L/min.
0.6 mL/min.
15°C
Data Acquistion
Detector mode
Replicate integrations
Mass range
Dwell time
Number of MCA channels
Number of scan sweeps
Total acquisition time
Pulse counting
3
8-240 amu
320 µs
2048
85
3 minutes per sample
1
The described instrument and operating conditions were used to determine the
scanning mode MDL data listed in Table 7 and the precision and recovery data given
in Tables 9 and 10.
200.8-40
TABLE 7: METHOD DETECTION LIMITS
Scanning Mode1
Total Recoverable
AMU
Element
27
123
75
137
9
111
52
59
63
206,207,208
55
202
98
60
82
107
205
232
238
51
66
Aqueous
µg/L
Selection Ion Monitoring Mode2
Total Recoverable
Direct Analysis3
Solids
mg/kg
Aqueous
µg/L
Aqueous
µg/L
Al
Sb
As
1.0
0.4
1.4
0.4
0.2
0.6
1.7
0.04
0.4
0.04
0.02
0.1
Ba
Be
Cd
0.8
0.3
0.5
0.4
0.1
0.2
0.04
0.02
0.03
0.04
0.03
0.03
Cr
Co
Cu
0.9
0.09
0.5
0.4
0.04
0.2
0.08
0.004
0.02
0.08
0.003
0.01
Pb
Mn
Hg
0.6
0.1
n.a.
0.3
0.05
n.a.
0.05
0.02
n.a
0.02
0.04
0.2
Mo
Ni
Se
0.3
0.5
7.9
0.1
0.2
3.2
0.01
0.06
2.1
0.01
0.03
0.5
Ag
Tl
Th
0.1
0.3
0.1
0.05
0.1
0.05
0.005
0.02
0.02
0.005
0.01
0.01
U
V
Zn
0.1
2.5
1.8
0.05
1.0
0.7
0.01
0.9
0.1
0.01
0.05
0.2
1
Data acquisition mode given in Table 6. Total recoverable MDL concentrations are
computed for original matrix with allowance for sample dilution during preparation.
Listed MDLs for solids calculated from determined aqueous MDLs.
2
MDLs determined using state-of-the-art instrumentation (1994). Data for75 As,77 Se,
and 82Se were acquired using a dwell time of 4.096 seconds with 1500 area count per
seconds 83Kr present in argon supply. All other data were acquired using a dwell
time of 1.024 seconds per AMU monitored.
3
MDLs were determined from analysis of seven undigested aqueous sample aliquots.
n.a. - Not applicable. Total recoverable digestion not suitable for organo-mercury
compounds.
200.8-41
TABLE 8: ACCEPTANCE LIMITS FOR QC CHECK SAMPLE
METHOD PERFORMANCE (µg/L)1
Element
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Manganese
Molybdenum
Nickel
Selenium
Silver
Thallium
Thorium
Uranium
Vanadium
Zinc
QC Check
Sample
Conc.
Average
Recovery
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100.4
99.9
101.6
99.7
105.9
100.8
102.3
97.7
100.3
104.0
98.3
101.0
100.1
103.5
101.1
98.5
101.4
102.6
100.3
105.1
Standard
Deviation2
(Sr)
Acceptance
Limits3
µg/L
5.49
2.40
3.66
2.64
4.13
2.32
3.91
2.66
2.11
3.42
2.71
2.21
2.10
5.67
3.29
2.79
2.60
2.82
3.26
4.57
84-117
93-107
91-113
92-108
88-1124
94-108
91-114
90-106
94-107
94-114
90-106
94-108
94-106
86-121
91-1115
90-107
94-109
94-111
90-110
91-119
1
Method performance characteristics calculated using regression equations from
collaborative study, Reference 11.
2
Single-analyst standard deviation, Sr.
3
Acceptance limits calculated as average recovery ± three standard deviations.
4
Acceptance limits centered at 100% recovery.
5
Statistics estimated from summary statistics at 48 and 64 µg/L.
200.8-42
TABLE 9: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES
DRINKING WATER
Sample
Conc.
Element µg/L
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
175
<0.4
<1.4
43.8
<0.3
<0.5
<0.9
0.11
3.6
0.87
0.96
1.9
1.9
<7.9
<0.1
<0.3
<0.1
0.23
<2.5
5.2
Low
Spike
µg/L
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
S (R)
115.8
99.1
99.7
94.8
113.5
97.0
111.0
94.4
101.8
97.8
96.9
99.4
100.2
99.0
100.7
97.5
109.0
110.7
101.4
103.4
5.9
0.7
0.8
3.9
0.4
2.8
3.5
0.4
8.8
2.0
1.8
1.6
5.7
1.8
1.5
0.4
0.7
1.4
0.1
3.3
RPD
0.4
2.0
2.2
5.8
0.9
8.3
9.0
1.1
17.4
2.8
4.7
3.4
13.5
5.3
4.2
1.0
1.8
3.5
0.4
7.7
High Average
Spike Recovery
µg/L
R (%) S (R)
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
102.7
100.8
102.5
95.6
111.0
101.5
99.5
93.6
91.6
99.0
95.8
98.6
95.2
93.5
99.0
98.5
106.0
107.8
97.5
96.4
1.6
0.7
1.1
0.8
0.7
0.4
0.1
0.5
0.3
0.8
0.6
0.4
0.5
3.5
0.4
1.7
1.4
0.7
0.7
0.5
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
200.8-43
RPD
1.1
2.0
2.9
1.7
1.8
1.0
0.2
1.4
0.3
2.2
1.8
1.0
1.3
10.7
1.0
4.9
3.8
1.9
2.1
1.0
TABLE 9: PRECISION AND RECOVERY DATA IN AQUEOUS
MATRICES (Cont’d)
WELL WATER
Sample
Conc.
Element µg/L
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
34.3
0.46
<1.4
106
<0.3
106
<0.9
2.4
37.4
3.5
2770
2.1
11.4
<7.9
<0.1
<0.3
<0.1
1.8
<2.5
554
Low
Spike
µg/L
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
S (R)
100.1
98.4
110.0
95.4
104.5
88.6
111.0
100.6
104.3
95.2
*
103.8
116.5
127.3
99.2
93.9
103.0
106.0
105.3
*
3.9
0.9
6.4
3.9
0.4
1.7
0.0
1.0
5.1
2.5
*
1.1
6.3
8.4
0.4
0.1
0.7
1.1
0.8
*
RPD
0.8
1.9
16.4
3.3
1.0
3.8
0.0
1.6
1.5
1.5
1.8
1.6
6.5
18.7
1.0
0.0
1.9
1.6
2.1
1.2
High Average
Spike Recovery
µg/L
R (%) S (R)
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
102.6
102.5
101.3
104.9
101.4
98.6
103.5
104.1
100.6
99.5
*
102.9
99.6
101.3
101.5
100.4
104.5
109.7
105.8
102.1
1.1
0.7
0.2
1.0
1.2
0.6
0.4
0.4
0.8
1.4
*
0.7
0.3
0.2
1.4
1.8
1.8
2.5
0.2
5.5
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
200.8-44
RPD
1.3
1.9
0.5
1.6
3.3
1.6
1.0
0.9
1.5
3.9
0.7
1.9
0.0
0.5
3.9
5.0
4.8
6.3
0.5
3.2
TABLE 9: PRECISION AND RECOVERY DATA IN AQUEOUS
MATRICES (Cont’d)
POND WATER
Sample
Conc.
Element µg/L
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
610
<0.4
<1.4
28.7
<0.3
<0.5
2.0
0.79
5.4
1.9
617
0.98
2.5
<7.9
0.12
<0.3
0.19
0.30
3.5
6.8
Low
Spike
µg/L
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
S (R)
*
101.1
100.8
102.1
109.1
106.6
107.0
101.6
107.5
108.4
*
104.2
102.0
102.7
102.5
108.5
93.1
107.0
96.1
99.8
*
1.1
2.0
1.8
0.4
3.2
1.0
1.1
1.4
1.5
*
1.4
2.3
5.6
0.8
3.2
3.5
2.8
5.2
1.7
RPD
1.7
2.9
5.6
2.4
0.9
8.3
1.6
2.7
1.9
3.2
1.1
3.5
4.7
15.4
2.1
8.3
10.5
7.3
14.2
3.7
High Average
Spike Recovery
µg/L
R (%) S (R)
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
78.2
101.5
96.8
102.9
114.4
105.8
100.0
101.7
98.1
106.1
139.0
104.0
102.5
105.5
105.2
105.0
93.9
107.2
101.5
100.1
9.2
3.0
0.9
3.7
3.9
2.8
1.4
1.8
2.5
0.0
11.1
2.1
2.1
1.4
2.7
2.8
1.6
1.8
0.2
2.8
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
200.8-45
RPD
5.5
8.4
2.6
9.0
9.6
7.6
3.9
4.9
6.8
0.0
4.0
5.7
5.7
3.8
7.1
7.6
4.8
4.7
0.5
7.7
TABLE 9: PRECISION AND RECOVERY DATA IN AQUEOUS
MATRICES (Cont’d)
SEWAGE TREATMENT PRIMARY EFFLUENT
Sample
Conc.
Element µg/L
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
1150
1.5
<1.4
202
<0.3
9.2
128
13.4
171
17.8
199
136
84.0
<7.9
10.9
<0.3
0.11
0.71
<2.5
163
Low
Spike
µg/L
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
S (R)
*
95.7
104.2
79.2
110.5
101.2
*
95.1
*
95.7
*
*
88.4
112.0
97.1
97.5
15.4
109.4
90.9
85.8
*
0.4
4.5
9.9
1.8
1.3
*
2.7
*
3.8
*
*
16.3
10.9
0.7
0.4
1.8
1.8
0.9
3.3
RPD
3.5
0.9
12.3
2.5
4.5
0.0
1.5
2.2
2.4
1.1
1.5
1.4
4.1
27.5
1.5
1.0
30.3
4.3
0.6
0.5
High Average
Spike Recovery
µg/L
R (%) S (R)
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
100.0
104.5
101.5
108.6
106.4
102.3
102.1
99.1
105.2
102.7
103.4
105.7
98.0
108.8
102.6
102.0
29.3
109.3
99.4
102.0
13.8
0.7
0.7
4.6
0.4
0.4
1.7
1.1
7.1
1.1
2.1
2.4
0.9
3.0
1.4
0.0
0.8
0.7
2.1
1.5
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
200.8-46
RPD
1.5
1.9
2.0
5.5
0.9
0.9
0.4
2.7
0.7
2.5
0.7
2.1
0.0
7.8
3.7
0.0
8.2
1.8
6.0
1.9
TABLE 9: PRECISION AND RECOVERY DATA IN AQUEOUS
MATRICES (Cont’d)
INDUSTRIAL EFFLUENT
Sample
Conc.
Element µg/L
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
44.7
2990
<1.4
100
<0.3
10.1
171
1.3
101
294
154
1370
17.3
15.0
<0.1
<0.3
0.29
0.17
<2.5
43.4
Low
Spike
µg/L
50
10
50
50
10
10
10
10
10
10
10
10
10
50
50
10
10
10
50
50
Average
Recovery
R (%)
S (R)
98.8
*
75.1
96.7
103.5
106.5
*
90.5
*
*
*
*
107.4
129.5
91.8
90.5
109.6
104.8
74.9
85.0
8.7
*
1.8
5.5
1.8
4.4
*
3.2
*
*
*
*
7.4
9.3
0.6
1.8
1.2
2.5
0.1
4.0
RPD
5.7
0.3
6.7
3.4
4.8
2.4
0.0
8.7
0.9
2.6
2.8
1.4
5.0
15.1
1.7
5.5
2.7
6.6
0.3
0.6
High Average
Spike Recovery
µg/L
R (%) S (R)
200
100
200
200
100
100
100
100
100
100
100
100
100
200
200
100
100
100
200
200
90.4
*
75.0
102.9
100.0
97.4
127.7
90.5
92.5
108.4
103.6
*
88.2
118.3
87.0
98.3
108.7
109.3
72.0
97.6
2.1
*
0.0
1.1
0.0
1.1
2.4
0.4
2.0
2.1
3.7
*
0.7
1.9
4.9
1.0
0.0
0.4
0.0
1.0
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
200.8-47
RPD
2.2
0.0
0.0
0.7
0.0
2.8
1.7
1.3
1.6
0.0
1.6
0.7
1.0
3.6
16.1
2.8
0.0
0.9
0.0
0.4
TABLE 10: PRECISION AND RECOVERY DATA IN SOLID MATRICES
EPA HAZARDOUS SOIL #884
+
Sample Low
Average
Conc.
Spike Recovery
Element (mg/kg) (mg/kg) R (%)
S (R)
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
5170
5.4
8.8
113
0.6
1.8
83.5
7.1
115
152
370
4.8
19.2
<3.2
1.1
0.24
1.0
1.1
17.8
128
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
*
69.8
104.7
54.9
100.1
97.3
86.7
98.8
86.3
85.0
*
95.4
101.7
79.5
96.1
94.3
69.8
100.1
109.2
87.0
*
2.5
5.4
63.6
0.6
1.0
16.1
1.2
13.8
45.0
*
1.5
3.8
7.4
0.6
1.1
0.6
0.2
4.2
27.7
High+ Average
Spike Recovery
RPD (mg/kg) R (%) S (R)
RPD
–
4.7
9.1
18.6
1.5
1.4
8.3
1.9
3.4
13.9
12.7
2.9
1.0
26.4
0.5
3.1
1.3
0.0
2.3
5.5
–
6.5
5.4
0.5
1.0
1.0
0.0
1.8
4.6
23.7
2.2
2.0
0.8
26.5
2.3
2.9
7.9
0.0
2.4
14.1
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
*
70.4
102.2
91.0
102.9
101.7
105.5
102.9
151.7
85.2
95.2
102.3
100.7
94.8
97.9
76.0
102.9
106.7
113.4
*
1.8
2.2
9.8
0.4
0.4
1.3
0.7
4.2
25.7
10.4
0.7
0.8
9.4
0.8
1.0
2.2
0.0
1.3
12.9
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
– Not determined.
+
Equivalent.
200.8-48
TABLE 10: PRECISION AND RECOVERY DATA IN SOLID MATRICES
NBS 1645 RIVER SEDIMENT
+
Sample Low
Average
Conc.
Spike Recovery
Element (mg/kg) (mg/kg) R (%)
S (R)
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
5060
21.8
67.2
54.4
0.59
8.3
29100
7.9
112
742
717
17.1
41.8
<3.2
1.8
1.2
0.90
0.79
21.8
1780
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
*
73.9
104.3
105.6
88.8
92.9
*
97.6
121.0
*
*
89.8
103.7
108.3
94.8
91.2
91.3
95.6
91.8
*
*
6.5
13.0
4.9
0.2
0.4
*
1.3
9.1
*
*
8.1
6.5
14.3
1.6
1.3
0.9
1.8
4.6
*
High+ Average
Spike Recovery
RPD (mg/kg) R (%) S (R)
RPD
–
9.3
7.6
2.8
0.5
0.0
–
2.6
1.5
–
–
12.0
4.8
37.4
4.3
3.6
2.6
5.0
5.7
–
–
3.9
2.9
3.9
0.2
3.9
–
0.0
1.8
–
–
0.9
0.0
15.1
1.9
1.3
2.8
3.5
0.8
–
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
*
81.2
107.3
98.6
87.9
95.7
*
103.1
105.2
–
–
98.4
102.2
93.9
96.2
94.4
92.3
98.5
100.7
*
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
– Not determined.
+
Equivalent.
200.8-49
*
1.5
2.1
2.2
0.1
1.4
*
0.0
2.2
–
–
0.7
0.8
5.0
0.7
0.4
0.9
1.2
0.6
*
TABLE 10: PRECISION AND RECOVERY DATA IN SOLID MATRICES
EPA ELECTROPLATING SLUDGE #286
Sample Low+ Average
Conc.
Spike Recovery
Element (mg/kg) (mg/kg) R (%)
S (R)
Al
Sb
As
Ba
Be
Cd
Cr
Co
Cu
Pb
Mn
Mo
Ni
Se
Ag
Tl
Th
U
V
Zn
5110
8.4
41.8
27.3
0.25
112
7980
4.1
740
1480
295
13.3
450
3.5
5.9
1.9
3.6
2.4
21.1
13300
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
*
55.4
91.0
1.8
92.0
85.0
*
89.2
*
*
*
82.9
*
89.7
89.8
96.9
91.5
107.7
105.6
*
*
1.5
2.3
7.1
0.9
5.2
*
1.8
*
*
*
1.2
*
3.7
2.1
0.9
1.3
2.0
1.8
*
High+ Average
Spike Recovery
RPD (mg/kg) R (%) S (R)
–
4.1
1.7
8.3
2.7
1.6
–
4.6
6.0
–
–
1.3
6.8
4.2
4.6
2.4
3.2
4.6
2.1
–
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
*
61.0
94.2
0
93.4
88.5
*
88.7
61.7
*
–
89.2
83.0
91.0
85.1
98.9
97.4
109.6
97.4
*
*
0.2
0.8
1.5
0.3
0.8
*
1.5
20.4
*
–
0.4
10.0
6.0
0.4
0.9
0.7
0.7
1.1
*
S (R) Standard deviation of percent recovery.
RPD Relative percent difference between duplicate spike determinations.
< Sample concentration below established method detection limit.
* Spike concentration <10% of sample background concentration.
– Not determined.
+
Equivalent.
200.8-50
RPD
–
0.9
1.5
10.0
0.9
0.5
–
4.6
5.4
–
–
1.0
4.5
18.0
1.1
2.4
2.0
1.8
2.5
–
TABLE 11: PRIMARY DRINKING WATER CONTAMINANTS
PRECISION AND RECOVERY DATA
Regional Sample
Background Concentration, µg/L
(IV)
(VI)
(X)
Average Mean1
% Recovery
Antimony
Arsenic
Barium
0.16
< MDL
4.6
0.07
2.4
280
0.03
1.0
14.3
114%
93
(*)
1.9
8.5
–
Beryllium
Cadmium
Chromium
< MDL
0.05
0.71
< MDL
0.05
5.1
< MDL
0.03
0.10
100%
81
94
8.2
4.0
2.5
Copper
Lead
Mercury
208
1.2
< MDL
130
1.2
0.23
14.3
2.5
< MDL
(*)
91
86
–
2.6
11.4
Nickel
Selenium
Thallium
1.7
< MDL
< MDL
3.6
4.3
0.01
0.52
< MDL
< MDL
101%
98
100
11.5
8.4
1.4
Analyte
S (R)
1
The three regional waters were fortified with 1.0 µg/L of all analytes listed, except
selenium, which was fortified to 20 µg/L.
(*) Recovery of barium and copper was not calculated because the analyte addition
was <20% the sample background concentration in all waters. (Recovery calculations
are not required if the concentration of the analyte added is less than 30% of the
sample background concentration. Section 9.4.3).
S (R) Standard deviation of the mean percent recoveries.
200.8-51
200.8-55
TABLE 13: BACKGROUND AND SPIKE MEASUREMENTS IN WASTEWATER
DIGESTATEa
Concentrate 1
Concentrate 2
Background
Std
Conc. Dev
µg/L µg/L
200.8-56
Be
Al
Cr
V
Mn
Co
Ni
cu
Zn
As
Se
Mo
Ag
Cd
Sb
Ba
Tl
Pb
Th
U
a
0.0
78.2
19.5
1.9
296.6
2.5
47.3
77.4
77.4
0.8
4.5
166.1
0.6
2.7
3.3
68.6
0.1
6.9
0.1
0.4
0.0
12.4
8.1
2.8
24.7
0.4
5.0
13.2
4.9
1.1
6.2
9.4
0.7
1.1
0.2
3.3
0.1
0.5
0.1
0.2
Std
Std
Spike Found Dev % Rec RSD Spike Found Dev % Rec RSD RSDr
µg/L µg/L µg/L
%
%
µg/L µg/L µg/L
%
%
%
100
200
200
250
125
125
125
125
200
200
250
100
200
125
100
250
100
125
125
125
94.5
260.9
222.2
271.8
419.0
124.7
161.7
194.5
257.4
194.9
236.8
269.8
176.0
117.0
100.2
321.0
103.3
135.1
140.2
141.2
11.8
41.2
23.3
36.5
35.7
12.3
4.9
29.5
16.3
8.0
14.2
19.0
14.6
4.8
4.8
19.4
8.0
7.8
19.5
19.3
94.5
91.4
101.4
108.0
97.9
97.8
91.5
93.7
90.0
97.1
92.9
103.7
87.7
91.4
96.9
101.0
103.2
102.6
112.1
112.6
12.5
15.8
10.5
13.4
8.5
9.9
3.0
15.2
6.3
4.1
6.0
7.0
8.3
4.1
4.8
6.0
7.7
5.8
13.9
13.7
125
250
250
200
100
101
100
100
250
250
200
125
250
100
125
200
125
100
100
100
118.1
309.1
274.3
219.3
397.4
100.7
142.7
172.3
302.5
244.7
194.3
302.0
214.6
96.6
125.9
279.3
129.2
110.3
113.3
113.6
14.7
48.5
26.6
30.1
34.8
9.4
5.6
26.6
21.1
12.8
9.3
18.0
17.8
3.2
4.3
17.2
8.9
6.3
15.4
16.0
94.5
92.4
101.9
108.7
100.8
97.2
95.4
94.9
90.0
97.6
94.9
108.7
85.6
93.9
98.1
105.4
103.3
103.4
113.2
113.2
12.4
15.7
9.7
13.7
8.8
9.3
3.9
15.4
7.0
5.2
4.8
6.0
8.3
3.3
3.4
6.2
6.9
5.7
13.6
14.1
Results from 10 participating laboratories. Wastewater digestate supplied with the study
materials. Mean background concentrations determined by the participants.
3.5
2.7
2.0
2.6
1.0
2.8
2.1
2.2
1.8
3.4
3.8
1.5
2.3
2.9
1.8
2.5
2.1
1.8
2.7
2.5
TABLE 14: SPIKE MEASUREMENTS IN PARTICIPANTS WASTEWATERa
Concentrate 1
Spike Found
µg/L µg/L
200.8-57
Be
Al
Cr
V
Mn
Co
Ni
cu
Zn
As
Se
Mo
Ag
Cd
Sb
Ba
Tl
Pb
Th
U
a
101
200
200
250
125
125
125
125
200
200
250
100
200
125
100
250
100
125
125
125
103.4
198.7
205.4
246.5
119.0
125.8
127.4
126.8
201.4
207.3
256.8
98.6
200.7
123.2
92.2
245.2
100.0
125.8
124.2
130.4
Std
Dev
µg/L
12.0
23.9
12.3
4.4
5.4
7.0
9.7
5.3
36.7
11.9
26.4
4.6
48.9
11.5
4.4
12.8
0.9
5.1
7.6
10.3
Concentrate 2
% Rec RSD
%
%
103.4
99.4
102.7
98.6
95.2
100.6
101.9
101.4
100.7
103.7
102.7
98.6
100.4
98.6
92.2
98.1
100.0
100.6
99.4
104.3
11.6
12.0
6.0
1.8
4.5
5.6
7.6
4.2
18.2
5.7
10.3
4.7
24.4
9.3
4.8
5.2
0.9
4.1
6.1
7.9
Spike Found
µg/L µg/L
Std
Dev
µg/L
128.2
252.4
253.4
196.8
95.5
99.5
101.0
105.3
246.4
263.0
214.0
123.2
231.2
95.8
119.0
204.7
128.0
100.8
99.8
106.4
13.6
15.5
15.4
2.8
4.3
5.3
7.5
3.6
29.7
2.6
18.7
6.7
63.5
2.9
1.0
12.1
6.0
2.7
5.7
6.8
125
250
250
200
100
101
100
100
250
250
200
125
250
100
125
200
125
100
100
100
% Rec
%
RSD RSDr
%
%
102.6
101.0
101.4
98.4
95.5
98.5
101.0
105.3
98.6
105.2
107.3
98.6
92.5
95.8
95.2
102.4
102.4
100.8
99.8
106.4
10.6
6.1
6.1
1.4
4.5
5.3
7.4
3.4
12.1
1.0
8.7
5.4
27.5
3.0
0.8
5.9
4.7
2.7
5.7
6.4
Results from five participating laboratories. Mean concentrations before spiking are not
listed because they varied considerably among the different wastewaters.
2.4
2.9
1.1
2.0
0.8
1.8
1.7
2.8
2.6
3.2
3.6
2.2
8.2
5.8
2.8
2.1
3.5
2.2
3.2
2.3
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