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Standard Operating Procedure for:
Total Suspended Solids
ID: TSSolids
Revision: 2
May 2007
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Table of Contents
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Identification of the test method ....................................................................... 3
Applicable matrix or matrices: .......................................................................... 3
Detection Limit.................................................................................................... 3
Scope of the test method ................................................................................... 3
Summary of test method.................................................................................... 3
Definitions ........................................................................................................... 3
Interferences ....................................................................................................... 3
Health and safety ................................................................................................ 4
Personnel qualifications .................................................................................... 4
Equipment and supplies .................................................................................... 4
Reagents and standards .................................................................................... 4
Sample collection, preservation, shipment and storage ................................ 4
Quality control .................................................................................................... 5
Calibration and standardization ........................................................................ 6
Procedure ............................................................................................................ 6
Data acquisition, calculations, and reporting .................................................. 8
Computer hardware and software ..................................................................... 8
Method performance .......................................................................................... 8
Pollution prevention ........................................................................................... 9
Data assessment and acceptable criteria for quality control measures ....... 9
Corrective actions for out-of-control or unacceptable data ........................... 9
Waste management ............................................................................................ 9
References .......................................................................................................... 9
Tables, diagrams, flowcharts and validation data ......................................... 10
Bench sheet ...................................................................................................... 11
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1
Identification of the test method
Determination of Total Suspended Solids
2
Applicable matrix or matrices:
This method is suitable for the determination of solids in potable and surface
waters and wastewaters with total suspended solids (TSS) of up to 20,000 mg/L.
3
Detection Limit
The desired detection limit for this method is 0.5 mg/L for a 1-L sample.
4
Scope of the test method
This standard operating procedure provides laboratory personnel with guidance
on the procedure for determining TSS. This method is limited to the determination of
TSS in water samples collected from natural bodies of water containing TSS of < 20,000
mg/L.
5
Summary of test method
The procedure described here follows Standard Methods (2005), 2540D and
EPA (1983) Method 160.2 (Residue, non-filterable). A well-mixed, measured volume of
a water sample is filtered through a pre-weighed glass fiber filter. The filter is heated to
constant mass at 104 ± 1º C and then weighed. The mass increase divided by the water
volume filtered is equal to the TSS in mg/L.
6
Definitions
6.1
Analytical batch: The set of samples processed at the same time
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6.2
Laboratory reagent blank (LRB): An aliquot of deionized water treated as a
sample in all aspects, except that it is not taken to the sampling site. The
purpose is to determine if the analytes or interferences are present in the
laboratory environment, the reagents, or the apparatus.
6.3
Laboratory duplicate (LD): Two aliquots of the same environmental sample
treated identically throughout a laboratory analytical procedure. Analysis of
laboratory duplicates indicates precision associated with laboratory procedures
but not with sample collection, preservation or storage procedures.
6.4
Method detection limit (MDL) -- The lowest level at which an analyte can be
detected with 99 percent confidence that the analyte concentration is greater
than zero.
Interferences
It is recognized that TSS measurements may include both positive errors
(occluded water and waters of crystallization) and negative errors (decomposition and
volatilization of minerals such as carbonates, as well as loss of solids that are small
enough to pass through the filter). See SM, 2540 A.2, B.1.b, and D.1.b for further
discussion of interferences for this method.
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8
Health and safety
8.1
The analysis involves handling of freshwater samples that may contain live
microorganisms and therefore pose some threat of infection. Laboratory
personnel who are routinely exposed to such water samples are encouraged to
protect themselves from water borne illnesses by wearing clean disposable
gloves and washing their hands frequently.
8.2
This analytical procedure uses a vacuum pump for the filtration steps. There is a
risk of implosion under some circumstances. The analyst should ensure that the
receiving flask is free from cracks or other imperfections.
9
Personnel qualifications
Laboratory and field personnel shall have a working knowledge of this analytical
procedure and will have received training from an associate knowledgeable of the
proper sample analysis procedures. Prior to the first batch of sample analyses, the
analyst will complete a demonstration of capability exercise as described below in the
Quality control section.
10
Equipment and supplies
10.1 Filters, Glass microfiber: 47 mm diameter, 1.5 µm nominal pore size, such as
Whatman 934-AH (catalog number: 1827 047) or equivalent
11
10.2
Filtration apparatus
a. Filter pump
b. A 1-L or 4-L receiving flask
c. Filter funnel manifold, 3 positions
d. Magnetic filter funnels 300 mL
e. Vacuum tubing, ¼” inside diameter
10.3
Drying oven adjusted to 104 ± 1ºC. Aluminum weighing dishes (or
10.4
equivalent).
10.5
Analytical balance capable of reading to 0.1 mg.
Reagents and standards
11.1 Deionized water (DI): water that has been passed through a purification system
(e.g., the Barnstead/Thermolyne system in 476 Temple).
11.2
12
There are no standards available for this method.
Sample collection, preservation, shipment and storage
12.1 See the SOP for water sample collection procedures (SOP: 1040R01 Water
Sampling.doc).
12.2
Bottles are sealed and placed on ice in a cooler for transport to the laboratory.
The samples are placed in a refrigerator in the laboratory. The maximum holding
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time is seven days (SM, 2005) but analysis should begin as soon as possible
upon delivery at the laboratory.
13
Quality control
13.1 Record the start and end temperatures for this analysis in the instrument log
book.
13.2
Method detection limit: Initial demonstration of capability (for any new laboratory
assistant) and quarterly thereafter;
a.
Carry ten filters through the procedure, filtering 1 liter of deionized water
for each.
b.
Calculate the standard deviation of the results. The method detection
limit is three times the standard deviation. The detection limit should be
less than or equal to 0.5 mg/L
13.3
Precision: Initial demonstration of capability (for any new laboratory assistant)
and quarterly thereafter;
a.
Collect 5 L of sample from the same site under conditions as close to
identical as practical. Ideally, the site should be chosen to have TSS ≥
10 mg/L.
b.
Carry out ten analyses using 300 mL samples for each.
c.
Calculate the average and standard deviation of the values.
d.
The standard deviation should be less than or equal to 20% of the
average value. If it is not, evaluate the procedures to identify sources of
error.
13.4
Laboratory Duplicate (LD) reproducibility: Carry out with each analytical batch of
filters.
a.
Carry out two replicates on the same sample, using a sample volume
sufficient to provide at least 5 mg solid (ideally, TSS > 10 mg/L).
b.
The relative percent difference (RPD) between the two TSS values
should be ≤ 20% of their average value.
c.
Use equation 1 to calculate RPD:
d.
13.5
Equation 1:
RPD (%) = (A – B) x 100%
(A + B)/2
Where:
A = mass of first aliquot (mg), and
B = mass of duplicate aliquot (mg)
Analyze one set of duplicates for every 10 samples analyzed.
Blank (LRB): At least one blank should be measured with each analytical batch
of filters.
a.
For the blank measurement, filter 1L deionized water.
b.
The TSS value for the blank should be less than 0.5 mg/L. If it is not,
evaluate the procedure and correct sources of error.
c.
Analyze one blank for every 10 samples analyzed.
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14
Calibration and standardization
There are no calibration or standardization procedures for this method.
15
Procedure
15.1 Balance operation:
a.
The analyst should review the latest revision of the SOP for balance
operation (SOP: 1010R01 Balance.doc) prior to using a balance for this
method.
b.
The balance should be level, clean and calibrated prior to use.
c.
Perform a balance check prior to each batch of analyses:
1.
Select a test weight (or combination of test weights) and place on
the balance pan.
2.
Record values on the bench sheet (see below) and in the balance
instrument log book.
15.2
Preparation of filters:
a.
Place filter disks onto the filtration apparatus. Apply vacuum and rinse
each with three successive 20-mL volumes of deionized water. Draw air
through the filters until it appears that all water has been drawn off.
b.
Place filters (in individual labeled aluminum evaporating dishes) in an
oven set to 104 ± 1ºC.
c.
Heat filters for a minimum of 1 hour to ensure that filters are dry.
d.
Remove filters from the oven and place them into a desiccator until they
have cooled to balance temperature.
e.
Weigh each filter, recording all measurements to 0.1 mg precision.
f.
Record the mass of the filter on the bench sheet as the Filter Tare Mass
in mg.
g.
Store filters in a desiccator until use.
15.3
Selection of sample volume
a.
The ideal mass increase for the TSS measurement is between 2 and 200
mg (minimum 1.0 mg). The volume of water sample needed to produce
this mass change depends on the TSS value.
b.
For water collected under base-flow conditions, the recommended
starting volume is 300 mL. However, if the suspended solids collected in
the filter are either too high or too low, or if the filtration becomes slow
due to clogging (total filtration time > 10 minutes), the volume should be
adjusted as indicated below.
1.
If the mass of the captured suspended solids is less than 1.0 mg,
repeat the analysis using a larger sample volume, up to 2 L.
2.
If the filtration becomes slow because of clogging, estimate the
filtration volume at which the filtration volume decreased and
repeat the procedure with a fresh filter, using a volume less than
that needed to significantly reduce filtration rate.
3.
Based on experience the analyst may adjust sample volume. If
filtration of 500 mL produces little observable solids on the filter,
the analyst may filter more of the water sample.
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4.
c.
If experience has shown that samples from a site normally have
very high levels of suspended solids and/or frequently cause
clogging, the analyst may reduce the sample volume, as long as
the mass of solid collected falls in the range of 2 to 200 mg.
For highly turbid samples or samples with expected high amounts of TSS:
1.
Place a magnetic stir bar into the sample bottle.
2.
Place the bottle onto a magnetic stirring unit.
3.
Stir at sufficient speed to create a vortex.
4.
Use a 20 mL volumetric pipette to remove sample from the bottle;
choose a point that is mid-depth and midway between the bottle
wall and the vortex to obtain a homogenous sample.
5.
Place the measured sample onto the filter and continue suction.
6.
Continue steps 15.3.d.4 – 5 until the volume added starts to slow
the filtration rate.
7.
Record the volume (in L) on the bench sheet.
8.
Rinse the filter pad with three 10 mL volumes of DI.
15.4 Procedures for TSS
a.
Set up the filtration apparatus, insert a filter, and apply vacuum.
b.
Wet the filter with a small volume of deionized water to seat it.
c.
Shake the sample vigorously and then measure out the predetermined
sample volume using a graduated cylinder. Record the volume filtered in
liters on the bench sheet.
d.
Rinse the graduated cylinder and filter with three 20 mL volumes of DI,
allowing complete drainage between washings.
e.
Continue suction for three minutes after filtration is complete.
f.
Carefully transfer the filter to an aluminum weighing dish, and place filter
on a cookie sheet or similar device.
g.
Place filters on sheet into an oven set to 104 ± 1ºC and dry for a minimum
of one hour.
h.
Remove filters from oven and transfer them to a desiccator to cool to
room temperature.
i.
Weigh one sample filter to the nearest 0.1mg. On the bench sheet record
the sample ID and the mass (Mass 1) in the “Weight check” section.
j.
Repeat steps 15.4.g. – i. Record the mass as “Mass 2” in the Weight
check section of the bench sheet. If the mass of the filter increases less
than 0.5 mg or the change in the mass of the solids is less than 4% of the
previously measured mass, then continue with TSS calculations.
k.
If the mass of the filter increases by more than 0.5 mg, repeat steps
15.4.g. – i. until the filter mass increase is less than 0.5 mg or the change
in the mass of the solids is less than 4% of the previously measured
mass. Record each additional mass on the bench sheet as “Mass 3”,
“Mass 4”, etc. Use the back of the bench sheet if necessary.
l.
Record the Oven Dry Mass (in mg) on the bench sheet.
m.
Calculate TSS as described below.
n.
Dump remaining sample down the drain, remove label, and rinse with tap
water to remove any solids from the bottle. Wash bottles according to the
Bottle Prep non-Metals SOP 0150R01.
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17
Data acquisition, calculations, and reporting
16.1 For each sample analyzed, including quality control samples, record the volume
filtered and oven dry mass in the appropriate places on the bench sheet (see
below). Calculate TSS using equation 2.
TSS (mg/L) = (A – B)
V
Where:
A = mass of filter + dried residue (mg),
B = mass of filter (tare weight) (mg), and
V = volume of sample filtered (L)
16.2
Results should be reported to 0.1 mg/L precision.
16.3
If multiple bottles were used to collect a composite sample across a stream
channel, analyze each bottle separately and calculate the average of the values
for the final TSS concentration. If flow and discharge have been calculated for
each subsection then calculate a flow-weighted average using the TSS
concentrations for each aliquot.
Computer hardware and software
17.1 Word: This document and attached bench sheet are prepared using Microsoft
Word. The Word document file name for this SOP is: 2010R01 TSS.doc
17.2
18
Equation 2.
Excel: Quality control charts are created using Excel.
Method performance
18.1 The desired performance criteria for this measurement are:
a. Detection limit: 0.5 mg/L
b. Precision: ± 20% RPD
a. Minimum Quantification Interval: 0.1 mg/L
18.2
Below are values of reproducibility at different TSS values for the TSS process
given in Standard Methods 2540 D (each for ten replicates by two different
analysts; water volume not specified):
TSS mass (mg/L)
Standard deviation
Coefficient of Variation (%)
15
5.2
33
242
24
10
1707
13
0.8
Both Standard Methods 2540 D and EPA 160.2 indicate that replicates should
agree within 5% of their average (e.g., a percent difference between the two
values of 10%). The data noted here show that reproducibility is much poorer for
samples with low TSS.
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19
Pollution prevention
All wastes from these procedures shall be collected and disposed of according to
existing waste policies
20
Data assessment and acceptable criteria for quality control measures
20.1 The analyst should review all data for correctness (e.g., calculations).
21
20.2
Precision values are calculated for pairs of duplicate analyses.
20.3
Record the precision values as a percent on the bench sheet.
20.4
The desired precision is ± 20% RPD.
20.5
The desired detection limit is 0.5 mg/L
20.6
The completed bench sheet is reviewed by the analyst’s supervisor
Corrective actions for out-of-control or unacceptable data
21.1 Quality control charts will be created for charting precision and blank values.
21.2
The results for precision and blank data are compared to the acceptable values
for this analysis; ± 20% and 0.5 mg/L, respectively.
21.3
If a precision value exceeds 20% RPD then the analyst should write in the
comments section of the bench sheet: “These data are associated with an out-ofcontrol duplicate analysis. The UCL = 20%.” Note: “UCL” is the Upper Control
Limit (i.e., 20%).
21.4
If a blank value exceeds 0.5 mg/L then the analyst should write in the comments
section of the bench sheet: “These data are associated with a blank value that
exceeds the detection limit of 0.5 mg/L.”
21.5
The samples cannot be reanalyzed because the sample volume will be depleted
after the initial analysis.
21.6
If data are unacceptable for any reason, the analyst should review their analytical
technique prior to conducting this analysis again.
22
Waste management
The wastes generated in this method are not hazardous. They can be discarded
in the following manner: the water, both filtrate and raw sample, can be discarded in the
laboratory sink and filter papers can be discarded with the paper trash.
23
References
23.1 Standard Methods for the Examination of Water and Waste Water. Method 2540
D, APHA, 21st Edition, 2005.
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24
23.2
“Residue, Non-Filterable – Method 160.2 (Gravimetric, Dried at 103 – 105ºC).”
EPA Methods for Chemical Analysis of Water and Wastes. EPA publication
600/4-79/020. March 1983.
23.3
Water Sample Collection. 2006. OEWRI SOP. Document name: 1040R01
Water Sampling.doc
23.4
Operation of Analytical Balances. 2006. OEWRI SOP. Document name:
1010R01 Balance.doc
Tables, diagrams, flowcharts and validation data
24.1 There are no tables, diagrams, flowcharts or validation data for this method.
24.2
See page 10 for the bench sheet. The analyst should make a copy of this form
for each analytical batch of samples to be analyzed.
25
Bench sheet
Data reviewed by:
Analyst: ________________________
Date analyzed: _________________
Balance check:
Sample
Identification
Selected mass: __________
Date
Collected
Weigh Pan
Label
Measured mass: __________
Filter Tare
Mass (mg)
Volume
Filtered (L)
Oven Dry
Mass (mg)
(B)
(V)
(A)
Total
Suspended
Solids (mg/L)
[(A - B) / V]
Weight check: Select one sample for weight check. If, after the second weighing, the mass change is ≤
0.5 mg or the change in mass is ≤ 4 % of the previous value, then do not repeat the oven drying cycle.
Continue with drying cycle and weight check until mass change is acceptable.
Sample: ____________ Mass 1 (mg): _______ Mass 2 (mg): _______ Mass 3 (mg): _______
Comments: __________________________________________________________________
____________________________________________________________________________
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