Thermo Fisher Scientific InGuard Cartridges Product Manual

for
TM
InGuard Cartridges
Product Manual for InGuardTM Cartridges
Page 1 of 16
Product Manual
for
InGuardTM Cartridges
InGuard Ag (P/N 074038)
InGuard H (P/N 074037)
InGuard Na (P/N 074036)
InGuard HRP (P/N 074034)
InGuard Na/HRP (P/N 074035)
© 2009 Dionex Corporation
Document No. 065345
Revision 01
November 2009
Document No. 065345-01
© 2009 Dionex Corporation
November 2009
Product Manual for InGuardTM Cartridges
Page 2 of 16
TABLE OF CONTENTS
SECTION 1 – INTRODUCTION............................................................................................................ 3
SECTION 2 – CARTRIDGES AND USAGE ........................................................................................ 4
2.1. Cartridge Overview.....................................................................................................................................4
2.1.1.
2.2.
2.3.
2.4.
2.5.
Example calculation of resin capacity.............................................................................................................4
System Configurations ................................................................................................................................5
Use of Concentrator Columns ..................................................................................................................10
Standard InGuard Use Conditions ..........................................................................................................10
InGuard Ag, Na and H..............................................................................................................................11
2.5.1.
Determination of Nitrite in Brine ..................................................................................................................11
2.6. InGuard HRP and Na/HRP......................................................................................................................13
2.6.1.
Removal of Organics from Whole Milk........................................................................................................13
Appendix A. Example Chromeleon Program,
Dual Injection Valves in ICS-3000 DC Column Compartment .................................. 15
Appendix B. Example Chromeleon Program,
ICS-1100/1600/2100 with Auxiliary Valve.................................................................... 16
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Product Manual for InGuardTM Cartridges
Page 3 of 16
SECTION 1 – INTRODUCTION
InGuardTM products are designed for in-line sample pretreatment. An autosampler or pump is used to pass the sample through
the cartridge to remove matrix components. The InGuard chemistries are suitable for matrix elimination of a wide variety of
sample types. Matrix elimination is a method of sample preparation that removes certain matrix species from a sample,
typically by specifically binding matrix species to a solid phase. Interfering compounds can be removed before the analyte
determination. The number of samples that can be treated with an InGuard product depends on the matrix composition,
concentration of compounds to be removed and the sample injection volume. The cartridges have very low backpressure but
the chemistries usually function optimally at flow rates between 0.5 and 2 mL/min. Since these products treat samples before
chromatographic separation, they are suitable for both standard bore and microbore IC systems.
The InGuard line of sample pretreatment cartridges includes five chemistries in 9 x 24 mm PEEK cartridges. The cartridges
have 10-32 end fittings and can be used with standard fittings in an ion chromatography (IC) system. The InGuard cartridges
contain some OnGuard phases, e.g., Ag, H, Na and some newly developed phases, e.g., HRP and Na/HRP. The cartridges can
be used singly or in series for multiple chemistries in an IC system. In this automated process, only the sample injection
volume is treated for analysis. The cartridge size has been optimized for volume and capacity so that, depending on the
application, one cartridge will treat from about 40 to more than 200 samples in an automated method. The limited sample
volume of generally from 5 to 100 μL which is treated and then trapped in a concentrator, is far less sample than that
necessary in comparable offline, e.g. OnGuard, methods.
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Product Manual for InGuardTM Cartridges
Page 4 of 16
SECTION 2 – CARTRIDGES AND USAGE
2.1. Cartridge Overview
This manual describes recommended automated sample pretreatment procedures and examples of use for each of the
cartridge types. A few minutes of pre-washing can be accomplished in the IC system on startup so manual cleaning is not
necessary. Several valve configurations are provided. Selection of a valve configuration depends on the available hardware
and on the matrix elimination chemistry used in the application.
Table 1 provides an overview of the InGuard cartridge products and Table 2 provides guidance on expected capacity.
Table 1
Recommended Cartridge Applications
Cartridge
Ag
Na
H
Functional Group(s)
Ag+-form sulfonate
Na+-form sulfonate
H+-form sulfonate
Mode of Use
Ion Exchange
Ion Exchange
Ion Exchange
HRP
Hydrophilic
divinylbenzene
Adsorption, π- π
bonding
Na/HRP
Dual Functionality
Ion exchange (Na)
and Adsorption
Example Applications
Removal of halides
Removal of cations
Removal of cations
pH adjustment
Removal of hydrophobic
species, azo and cyanocontaining species
Remove Ca2+ (Na) and
lipids (HRP) from dairy
Table 2
InGuard Capacity
Cartridge Type
9 x 24 mm PEEK
Ag
H
Na
HRP
Na/HRP
2.1.1.
meq/cartridge
5-5.5
5-5.5
5-5.5
2 g resin
50%Na/50% HRP
Example calculation of resin capacity
A 1% sodium chloride sample contains 10 g NaCl/L sample. Of this 10 g NaCl, 35.45/58.45 is chloride, or 6.1 g. To convert
to mEq, 6.1 g chloride/ 35.45 g/mole = 0.17 mol or 170 mmol or 170 mEq/1000 mL or 0.17 mEq/mL. A 100 µL injection of
1% NaCl contains 0.017 mEq chloride. A cartridge containing 5 mEq of Ag+ can treat a maximum of 5/0.017 = 290 samples
of 1% NaCl. Other matrix components such as bromide and phosphate will also use some of this capacity. Some of the silver
chloride precipitate will re-dissolve, as discussed in the application. The figure below shows the amount of chloride
remaining after treatment, from a sample containing 250 ppm chloride, compared to no sample treatment.
The cartridge inlet is marked with the product label and must be connected towards the loading device as it contains a flow
distributor. The outlet contains a standard bed support to contain the resin in the cartridge.
!
CAUTION
Flow must always be in the indicated direction; otherwise, damage to the chromatographic system may
occur.
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Product Manual for InGuardTM Cartridges
Page 5 of 16
2.2. System Configurations
Optimum performance is achieved when the InGuard cartridge(s) is used to treat the contents of an injection loop and the
treated sample is then loaded onto a concentrator column. This configuration is shown in Figure 1 and can be accomplished
on any IC with two 6-port, a 6-port and a 10-port, or two 10-port valves. By using a defined loop volume and a concentrator
column, the need to time sample preparation in order to obtain an undiluted injection volume is avoided. In addition, smaller
sample volumes can be treated thus extending the life of the InGuard cartridge.
Figure 1
Preferred Configuration 1:
Two 6-port Valves and Two Pumps
Detector
AutoSampler
Suppressor
InGuard
Cartridge
S
Analytical
L
Column
W
C
L
P
Guard
Trap
Column
Column
6
1
5
2
Waste
4
3
Loading
Pump
Concentrator
Column
Waste
Pump
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Product Manual for InGuardTM Cartridges
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IonPac AG/AS15, 4-mm
23 mM KOH
1 mL/min
InGuard Ag and Na
100 uL
Suppressed conductivity, ASRS 300
Column:
Eluent:
Flow rate:
Sample Prep:
Injection vol:
Detection:
1
7
Sample
1.6% NaCl blank without InGuard
1.6% NaCL blank with InGuard Ag and Na
Water blank with InGuard
Std of 2ppm nitrite, sulfate, nitrate in 1.6% NaCl using InGuard
1.6% NaCl w/o
InGuard
1
Peaks:
Chloride
Nitrite
Carbonate
Nitrate
Sulfate
µS
2
mg/L
2
2
2
4
3
5
4
3
0 2
1
5
10
15
20
25
30
35
Minute
The key aspects of the system shown in Figure 1 include:
1. Two independently controlled valves such as 2 injection valves or 2 high pressure auxiliary valves from an ICS3000 DC module; or an injection valve and auxiliary valve in an ICS-1100/1600/2100 (ICS-1100 series)
instrument.
2. Two pumps such as from an ICS-3000 DP; or ICS-3000 SP or an ICS-1100 series instrument plus an AXP
pump. The second pump is a used to load the loop contents through the InGuard column and onto the
concentrator. The backpressure of the InGuard and concentrator columns together should be under 120 psi.
3. An ATC-3 column (for anion analysis) or an Electrolytic Water Purifier (EWP, P/N 071553) is used to clean the
water used to load the concentrator. If an EWP is used the loading pump is not required.
4. Sample volume is controlled by the autosampler/injection loop with a pressure limit of about 100 psi.
5. Eluent (DI water) reservoirs can be pressurized with 5 psi of clean Helium or Nitrogen in order to minimize
blanks.
6. Note that flow across the concentrator column to the analytical column should be in the reverse direction to the
flow across the concentrator when it is being loaded. This minimizes peak broadening in the analysis.
Figure 2 shows a plumbing configuration where the cell effluent is recycled for sample prep. The Electrolytic Water Purifier
(EWP) is used to clean the cell effluent water for trace work.
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Product Manual for InGuardTM Cartridges
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Figure 2
Preferred Configuration 2:
Two 6-port Valves, one pump and Electrolytic Water Purifier
Detector
Electrolytic
Water Purifier
AutoSampler
Suppressor
InGuard
Cartridge
S
Analytical
L
Column
W
C
L
P
Guard
Column
S
Waste
L
W
C
L
Concentrator
Column
Waste
Pump
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Product Manual for InGuardTM Cartridges
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Figure 3 shows a plumbing configuration where a 10-port valve replaces the second of the 6-port valves in Figure 1. In this
arrangement water does not flow over the InGuard cartridges between runs so the re-dissolution of silver halide precipitates
(formed during the removal of halides in the matrix) is much reduced. This configuration usually produces a higher sulfate
blank than the constant flow configurations.
Figure 3
Preferred Configuration 3:
One 6-port and One 10-port Valve and Two Pumps with Stopped Flow
Detector
Suppressor
AutoSampler
Analytical
Column
InGuard
Cartridge
S
L
W
Guard
Column
C
L
P
6
5
7
8
Waste
4
9
3
1
10
Concentrator
Column
2
Loading Pump
Waste
Pump
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Product Manual for InGuardTM Cartridges
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Figure 4
Preferred Configuration 4:
One One 6-port and One 10-port Valve and Two Pumps with Constant Wash
This configuration is used to minimize sulfate blank although the chloride peak will be larger than when a configuration with
stopped flow is used.
Detector
Suppressor
AutoSampler
Analytical
Column
InGuard
Cartridge
S
L
Guard
Column
W
C
L
P
6
Concentrator
Column
5
7
8
4
9
3
Waste
1
10
2
Loading Pump
Waste
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Pump
© 2009 Dionex Corporation
November 2009
Product Manual for InGuardTM Cartridges
Page 10 of 16
2.3. Use of Concentrator Columns
The use of concentrator columns in this system allows the collection of all treated sample ions for analysis using standard
injection volumes. InGuard cartridges have sufficiently low backpressure to be used on an AS autosampler directly in line
with the analytical columns, but more sample must be treated in order to obtain an undiluted sample segment for analysis.
2.4. Standard InGuard Use Conditions
The InGuard cartridge format is a 9 x 24 mm I.D PEEK column body with 10-32 end fittings for easy installation in an IC
system. The cartridges contain approximately 2.2 g of resin. The backpressure generated at 2 mL/min flow is less than 50 psi
which is compatible with the backpressure limits of syringe-type autosamplers including the AS and AS-DV. Depending on
the exact chemistry and types of samples treated, some cartridges can be regenerated.
The cartridge inlet is marked with the product label and must be connected towards the loading device as it contains a flow
distributor. The outlet contains a standard bed support to contain the resin in the cartridge.
!
Backwards flow will result in loss of resin, plugging of the chromatograph and possible damage to it.
NOTE
The volume necessary for complete sample loading through the InGuard cartridge(s) and onto the concentrator column can be
determined by an experiment as shown in Table 3. Enough volume needs to be pumped through the InGuard cartridge to
displace the entire sample, while at the same time displacing the minimum possible amount of the trapped matrix.
This is particularly noticeable when using an Ag cartridge to remove halides. Silver halides will redissolve in excess loading
water so only enough transfer water should be used to fully transfer the sample. For halide removal with tandem Ag and Na
cartridges in series with a 100 μL sample loop, a loading volume of 2-4 mL is sufficient.
Table 3
Optimizing Sample Prep Time using Two InGuard Cartridges
InGuard Ag and Na
cartridges with
100 µL sample loop
Loading volume (mL)
1 (0.5 mL/min x 2 min)
1.5
2.0
4.0
Peak Area (μS*min)
50 ppb Nitrate in
16,000 ppm Chloride
0
0.022
0.028
0.025
Peak Area (μS*min)
Chloride residual from
16,000 ppm Chloride
3
7
19
36
Table 4
General use parameters for InGuard cartridges.
Type
Ag
H
Na
HRP
Pump 2 Loading
Solvent
AS* and Pump 2
Maximum Flow rate
(mL/min)
2
2
2
2
DI water
DI water
DI water
100% DI water to
100% solvent
Na/HRP
DI Water
2
* AS Syringe Speed setting of 2, 3 or 4 is recommended.
Document No. 065345-01
Void
volume (μL)
Expected
Backpressure (psi)
850
850
850
850
50
50
50
50
850
50
© 2009 Dionex Corporation
November 2009
Product Manual for InGuardTM Cartridges
Page 11 of 16
2.5. InGuard Ag, Na and H
InGuard Ag cartridges contain 40 µm diameter Ag+ form sulfonated styrene-divinylbenzene (S-DVB) resin beads, the same
material used in OnGuard II Ag cartridges. Matrix elimination using this cartridge is based on the very low solubility of
silver salts, halides and some other anions. Since the salts are not infinitely insoluble, the precipitate can re-dissolve to some
extent. The chemical process for this matrix elimination requires the displacement of Ag+ from the resin by sample cations
and the subsequent precipitation in the ion exchange bed. The small amount of silver ion that redissolves should be trapped
using a Na+ or H+ InGuard cartridge placed after the InGuard Ag cartridge. This will avoid fouling of downstream cation
exchangers including the suppressor. The use of the Na or H cartridge after the Ag cartridge should be standard practice.
InGuard Ag cartridges have a fixed capacity and cartridge lifetime which will depend on sample matrix, injection volume,
etc. Due to the consumption of silver as discussed above, the halide matrix peak will gradually increase over the lifetime of
the cartridge. It is not recommended to re-use partially expended Ag cartridges as the size of the chloride peak from redissolution of AgCl, will be higher.
InGuard Na and H cartridges contain 40 µm Na+ form or H+ form S-DVB resin beads, the same as that used in OnGuard II
cartridges. They remove cations including metals by cation exchange governed by the standard selectivity of sulfonated
resins for cations. A partial selectivity series for these resins is H+ < Na+ < K+ < Ca 2+ < transition metals (as cations);
multiply charged cations are more highly retained than monovalent ions. Relative concentration also affects selectivity; ions
present in higher concentration can elute ions present in relatively lower concentration.
2.5.1.
Determination of Nitrite in Brine
The most common application for the Ag cartridge is the removal of chloride from high chloride samples for the
determination of ppm concentrations of other anions. As noted above, the Ag cartridge must be used in tandem with an
InGuard Na or H cartridge. The Na cartridge will not acidify the sample as does InGuard H. It should be chosen for situations
where the sample is pH sensitive, for example, in the determination of nitrite. Nitrite is readily oxidized to nitrate at low pH.
The system can be configured as shown in Figure 1, Figure 2 or Figure 3.
Figure 1 shows a system configured with two 6-port valves, two pumps and features a continuous wash of the InGuard
cartridges throughout the run. The Figure 2 configuration is very similar except that the system uses only one pump and the
detector cell outlet fluid is used in a recycle arrangement with an Electrolytic Water Purifier. The Figure 3 system uses one 6port valve and one 10-port valve with two pumps. In this arrangement the flow of the pump supplying DI water for the
sample preparation is diverted during the run so that no water flows over the InGuard cartridge stack during a run. This helps
minimize dissolution of the silver halide precipitates.
The cartridges can be used with standard bore or microbore columns since they are used for sample pretreatment during
loading of a concentrator column. The sulfate blank will be approximately 50 ppb, depending on flow rate and the age of the
cartridge.
Figure 5 is an overlay of a water blank, a 1.6% NaCl blank and a standard containing 2 ppm nitrite, sulfate and nitrate in
1.6% NaCl.
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Product Manual for InGuardTM Cartridges
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Figure 5
Analysis of Nitrite, Nitrate and Sulfate in Brine
Column:
Suppressor:
Concentrator:
Eluent:
Flow rate:
Column compartment temp:
Injection volume:
Sample rep:
Sample loading pump:
Concentrator loading time:
IonPac® AG15 guard column and AS15 analytical column (4 x 250 mm)
SRS 300, 4-mm, external water mode (15 psi)
TAC-LP1 concentrator column
23 mM KOH
1 mL/min
30 °C
100 μL
InGuard Ag followed by InGuard Na
DI water, 1 mL/min
4 min.
1
7
Sample
•
•
•
1
Peak
1
2
3
4
5
µS
2
3
4
5
3
1.6% NaCl blank
Water blank
Std of 2 ppm nitrite, sulfate, nitrate in 1.6%
NaCl
Analyte
Chloride
Nitrite
Carbonate
Nitrate
Sulfate
mg/L
2
2
2
0 1
5
10
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20
25
30
35
© 2009 Dionex Corporation
November 2009
Product Manual for InGuardTM Cartridges
Page 13 of 16
2.6. InGuard HRP and Na/HRP
InGuard HRP cartridges contain a 35 μm hydrophilic reversed phase resin based on divinylbenzene. The material has a
surface area of about 300 m2/g. Since this material is water-wettable, 100% aqueous samples can be applied without
disruption of the column bed. This material can be used to remove organic matrix material over a wide range of
hydrophobicity.
.
InGuard Na/HRP contains a blend of Na+-form sulfonated resin and HRP resin to provide the dual functionality of removing
both cations including metals and organic contaminants from a sample. This cartridge is designed to provide general purpose
cleanup of samples for anion analysis.
2.6.1.
Removal of Organics from Whole Milk
Figure 6 shows the determination of nitrite in whole milk after the removal of organic materials such as lipids and proteins
using InGuard HRP. The goal of sample preparation in this application is to achieve a stable retention time for the analytes.
This is achieved by removal of organic material that fouls the analytical column. InGuard Na/HRP can also be used for this
application to remove both Ca2+ and organic components of the milk. Table 5 provides results from 180 injections of whole
milk on one HRP cartridge using the method described below. The combination of the AG15 and AS20 is effective for
resolving the nitrite and nitrate both from each other and from matrix.
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Product Manual for InGuardTM Cartridges
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Figure 6
Analysis of Nitrite and Nitrate in Whole Milk
Column:
IonPac® AG15 guard column and IonPac® AS20 (4x50mm)
Eluent source: Eluent generator
Gradient steps: Time (min)
conc. (mM)
-20.0
50
-5.1
50
-5.0
14
0.0
14
17.1
14
17.1
50
20.0
50
Flow rate:
1.0 mL/min
Sample volume: 10 µL
Column oven: 30 °C
Detection:
Suppressed conductivity; ASRS® 300 4-mm, external water mode.
Sample:
Treated whole milk spiked with 40 ppb nitrite.
Peaks:
1. Nitrite
2. Nitrate
1
µS
2
1
0
4
10
Minute
15
20
Table 5
Summarized Results from 180 Injections of Whole Milk
Injection no.
1-60
61-180
% Retention time reduction
(nitrate) from Injection 1
<0.4%
<1.25%
Samples were prepared by dilution with an equal volume of 100% acetonitrile. Samples were allowed to stand for 30
minutes. The supernatant was sampled and this fraction analyzed by IC (10μL injection volume). The fouling rate was
measured by calculating the retention time reduction of nitrate detected by the IC. Based on this data, the capacity limit using
this method was determined to be approximately 60 samples/cartridge.
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Product Manual for InGuardTM Cartridges
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Appendix A. Example Chromeleon Program, Dual Injection Valves in ICS-3000
DC Column Compartment
The following steps in a PGM will load a loop, perform the sample preparation, load the concentrator column and start the
analysis, using the valving shown in Figure 1, where both valves are installed in an ICS-3000 DC column compartment.
Valve nomenclature follows the default conventions of the Chromeleon Server Configuration.
;this valving pumps water through the sample loop and the InGuard column; eluent is
pumped through the analytical column and concentrator column
InjectValve_1.State =
InjectValve_2.State =
InjectPosition
InjectPosition
0.000
;this valving connects the AS to the sample loop, water goes to InGuard; eluent is
pumped through analytical column and concentrator column
InjectValve_1.State =
InjectValve_2.State =
Load
Wait
Inject
Wait
Sampler.ReleaseExclusiveAccess
LoadPosition
InjectPosition
CycleTimeState
InjectState
;this valving directs loading water through the sample loop, the InGuard and the
concentrator column to waste; eluent flows directly to analytical column
0.1
InjectValve_1.State =
InjectValve_2.State =
InjectPosition
LoadPosition
; this valving places concentrator column in line with eluent and the analytical
column; the time point below (4.0)can be adjusted to optimize sample loading to
concentrator (see section 2.4)
4.0
InjectValve_1.State =
InjectValve_2.State =
CD_1.AcqOn
Autozero
LoadPosition
InjectPosition
The system configuration is set up so that the Left High Pressure Valve is controlled by the AS autosampler and the Right
High Pressure Valve is controlled by the ICS-3000 DC module (setup in Server Configuration). This is a logically convenient
arrangement if the AS is physically located to the left of the ICS-3000 DC.
Other valve configurations are possible, of course, including having one valve located in the ICS-3000 DC column
compartment and the other installed in an ICS-3000 DC Automation Manager. In this case, the second valve’s default name
from Server Configuration would be AM_HP1, states A and B. The flow path for AM_HP1 State B should be verified to be
through the concentrator column, in the reverse direction to the loading flow.
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Product Manual for InGuardTM Cartridges
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Appendix B. Example Chromeleon Program, ICS-1100/1600/2100 with Auxiliary
Valve.
The following steps in a PGM will load a loop, perform the sample preparation, load the concentrator column and start the
analysis, using the valving shown in Figure 1 where both valves are installed in an ICS-1100, ICS-1600 or ICS-2100.
;this valving pumps water through the sample loop and the InGuard column; eluent is
pumped through the analytical column and concentrator column
Pump_InjectValve.State =
Valve_2.State =
InjectPosition
B
0.000
;this valving connects the AS to the sample loop, water goes to InGuard; eluent is
pumped through analytical column and concentrator column
Pump_InjectValve.State =
Valve_2.State =
Load
Wait
Inject
Wait
Sampler.ReleaseExclusiveAccess
LoadPosition
B
CycleTimeState
InjectState
;this valving directs loading water through the sample loop, the InGuard and the
concentrator column to waste; eluent flows directly to analytical column
0.1
Pump_InjectValve.State =
Valve_2.State =
InjectPosition
A
; this valving places concentrator column in line with eluent and the analytical
column; the time point below can be adjusted to optimize sample loading to
concentrator (see section 2.4)
4.0
Pump_InjectValve.State =
Valve_2.State =
CD_1.AcqOn
Autozero
LoadPosition
B
The system configuration is set up so that the left high ressure valve is controlled by the AS autosampler as the default
injection valve and the right high pressure valve (auxiliary valve) is controlled by the ICS module. This is a logically
convenient arrangement if the AS is physically located to the left of the IC. The flow path for Valve_2 State B should be
verified to be through the concentrator column, in the reverse direction to the loading flow.
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November 2009