ARA Ion Chromatography Analysis
Revision 0.0
10/30/2007
Standard Operating Procedure Using
Ion Chromatography for the
Analysis of Anions & Cations in Ambient Air Particulate
Matter
Effective Date:10/30/2007
Version 1.0
Reviewed By:__________________________
Technical Director
Approved By:_________________________
Author: Mike Fort_______________________
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TABLE OF CONTENTS
Page
Table of Contents…………………………………………………………………………………………………………………………...........2
1.0 Scope and Application……………………………………………………………………………………………………………………….3
2.0 Summary…………………………………………………………………………………………………………………………………………..3
3.0 Definitions…………………………………………………………………………………………………………………………………………3
4.0 Interferences…………………………………………………………………………………………………………………………………….5
5.0 Safety………………………………………………………………………………………………………………………………………………..6
6.0 Equipment & Supplies……………………………………………………………………………………………………………………….6
7.0 Eluent Generation……………………………………………………………………………………………………………………………..7
8.0 Calibration & Standardization……………………………………………………………………………………………………………8
9.0 Sample collection, preservation, shipment, storage………………………………………………………………………….9
10.0 Quality control & Quality assurance………………………………………………………………………………………………..9
11.0 Filter/denuder extraction………………………………………………………………………………………………………………10
12.0 Ion Chromatography analysis………………………………………………………………………………………………………..11
13.0 Calculations…………………………………………………………………………………………………………………………………..12
14.0 Method Performance…………………………………………………………………………………………………………………...12
15.0 Maintenance…………………………………………………………………………………………………………………………………12
16.0 Pollution Prevention……………………………………………………………………………………………………………………..13
17.0 Waste Management……………………………………………………………………………………………………………………..13
18.0 References…………………………………………………………………………………………………………………………………….13
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1.0 Scope and Application
This procedure is for the analysis of anions and cations by ion chromatography collected on filter
samples located within the southeast United States. It is applicable for fine and course atmospheric
particles. Fine particles being less than 2.5microns is size and coarse particles being 2.5-10microns is
size. The sizes of filters used to capture the particulate matter are 47mm and 37mm respectively. The
air samples are collected by site operators and sent to the laboratory for analysis. The samplers used
are Particle Composition Monitors (PCM).
2.0 Summary
This method covers the simultaneous instrumental analysis of anions and cations by dual channel ion
chromatography. The filters are sent to the lab from the site operators in the field and equilibrated in
an ISO-6 clean room before extraction and analysis. Filters are extracted in DI water and injected into
the calibrated ion chromatography system for quantitation. The ions are speciated and detected by
passing thru a guard column, analytical column, suppressor and conductivity detector. Data acquisition
is acquired thru the use of Chromeleon software provided by Dionex. Below is a list of anions and
cations that may be quantitated with this standard operating procedure:
ANIONS
CATIONS
Bromide
Ammonium
Bromate
Calcium
Chlorate
Lithium
Chloride
Magnesium
Chlorite
Potassium
Fluoride
Sodium
Nitrate
Nitrite
Ortho-phosphate
Sulfate
3.0 Definitions
Batch: Indicates a volume of filters/denuders (20 or less) to signify an extraction batch. A new batch is
generated for every 20 samples extracted. If a batch was generated with less than 20 samples on one
day then a new batch must be created the following day.
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Calibration Blank (CB): A solution that has been prepared in the laboratory along with the calibration
standards using all the reagents involved in calibrating the IC. The blank must match the matrix of the
calibration standards. This would be just DI water in this case. The CB may be involved in the linear
regression calculation based upon the operators settings.
Calibration standard (CAL): A standard prepared in the laboratory that contains DI water plus a certain
concentration of the analytes of interest. These are usually made fresh daily. More than one
calibration sample is used to calibrate the Ion Chromatography system. This is usually 3 or more and a
calibration blank (CB).
Continuing Calibration Verification Standard (CCV): This standard is the midpoint of the calibration
curve. This is for the validation of linearity and continuous analysis of the analytical sequence. The CCV
is run after the initial calibration and before the continuing calibration blank (CCB).
Continuing Calibration Blank (CCB): This standard is used to verify the continuing validation of low end
linearity and contamination during the analytical sequence. It also serves as a good indicator of S/N
values over time. The CCB is run after the CCV, at a 10% frequency thereafter and at the end of the
analytical sequence.
Lab Blanks or Trip Blanks (LB or TB): These blanks consist of Teflon 47mm and 37mm filters. The blanks
will be run per lot (typically 100 filters per lot). One blank will be selected from the lot and analyzed for
anions and cations. The ions quantitated will represent the background inherent in the respective lot of
filters tested.
Field Blanks (FB): This type of blank will be sent out to the field from the laboratory. The filter will be
exposed to passive sampling in order to represent any contamination in the field. The blank will then be
shipped back to the lab for analysis and treated as an actual sample. Approximately 10% of all samples
are designated as field blanks (10 out of 100).
Field Duplicates or Collocated Samples (FD & C1 & C2): These are two separate samplers collecting
individual filter samples at the same time, location and same model of sampler. Usually, the only
difference will be the volume collected. Analysis of these duplicates contains information on sampling
efficiency, storage and preservation. These will be on an as needed basis or the frequency determined
by the technical director. Replicates may be run on the duplicates to determine instrument precision.
Laboratory Control Sample (LCS): This is a spiked sample (namely DI water) carried throughout the entire
extraction and instrumentation process to simulate method precision and accuracy. This sample is
spiked with a known amount of analytes to be determined.
Laboratory Control Sample Duplicate (LCSD): Sample spiked with a known amount of analytes. This
sample is carried throughout the extraction and instrumentation process to simulate method precision
and accuracy. The LCSD may or may not be determined due to lack of sample volume.
Matrix Spike (MS): A certain known amount of concentrated analytes spiked onto a sampled filter. This
filter is then carried throughout the extraction process and analyzed to determine the amount
recovered. The amount recovered is calculated and compared to the original values in the unspiked
sample. This is used for precision and accuracy, as well as, an indicator of the matrix spike recovery
limits.
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Matrix Spike Duplicate (MSD): A certain known amount of concentrated analytes spiked onto a sampled
filter. This will be an additional spike from the filter selected to do the matrix spike. A duplicate is done
to observe method precision. The percent recovery is calculated from the original values of the
unspiked sample. The results of the MS/MSD are calculated and compared. The precision and bias are
control charted on an ongoing basis. There may or may not be any matrix spike duplicates due to the
lack of sample volume.
Laboratory Reagent Blank, Method Blank, Prep Blank (LRB,MB,PB): These terms are all used
interchangeably. They are the same unless otherwise stated. One LRB, MB or PB will be run per batch
of 20 samples or less. This blank is an aliquot of water carried throughout the extraction/analytical
process just like a real sample. It’s used to signify background contamination or ions that are present in
the laboratory environment.
Linear Range Standard (LRS): A standard prepared in the laboratory using a known concentration of an
analyte that establishes the extrapolated range of the calibration curve. Each anion and cation of
interest must establish this linear range criterion. This end point is used to extrapolate the highest point
in the calibration curve to this linear range standard.
Method Detection Limit (MDL): The lowest concentration of an analyte that can be quantified and
reported with 99% confidence that the analyte concentration is greater than zero. A good starting point
for the MDL is 3 to 5 times the IDL.
Method Reporting Limit (MRL): This is ascertained by multiplying the MDL by 3 or 5.
Particulate Matter (PM): General term used to describe air born particles that are caused by
anthropogenic processes that contribute significantly to air pollution.
Quality Control Standard (QCS): A standard used to check the validity of the calibration curve. The QCS
is from a different manufacturer than the calibration standards. The QCS is usually made up of multiple
analytes at the same or differing concentrations.
Duplicates: Two samples extracted and analyzed with the same origin. These samples are used for
method precision.
4.0 Interferences
Interferences are laboratory, instrument, operator or matrix born. These can be eliminated by taking
special precautions while preparing your sample to be analyzed. Anything that comes in contact during
sample prep and analysis could be a potential interference. However, co-elution interferences are most
common and are corrected by diluting or lowering the eluent strength. Interferences are corrected by
having 100% resolution between peaks of interest (i.e. no overlap) over a small and large range of
concentrations.
4.1 Filter samples suspected of particles larger than 0.45micron. Filter solutions with particles larger
than 0.20micron. These particles may clog up the capillary lines in the Ion Chromatography system.
4.2 If any ClO2 is suspected in the sample, purge the sample with an inert gas (i.e. Argon, Nitrogen).
Residual ClO2 may form ClO3 prior to analysis.
4.3 To inhibit bacteria growths in extracts try to refrigerate as much as possible.
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4.4 Some low molecular weight amines may have retention times similar to the cations of interest.
Trimethylamines, triethylamines etc….
4.5 High levels of Na may interfere with NH4+. This will be validated during the initial demonstration by
running high levels of Sodium.
4.6 The acidity of the extract can cause problems if it’s lower than 2.0 H+ (pH). Historically, filter extracts
pH should be between 4.00-6.00 H+ (pH). The acidity of extracts shouldn’t be a problem.
4.7 Use plastic ware for solutions, standards and prepared samples since Na is a common contaminant
and may be leached from glassware.
5.0 Safety:
Laboratory personnel are responsible for wearing appropriate attire while performing this operational
procedure. Material Safety Data Sheet (MSDS) should be available and encouraged to explore. Be
aware of eye wash and spill cleanup locations at all times. Chemicals should be handled in a fume hood
where applicable.
6.0 Equipment and Supplies:
This SOP is applicable to analysts that are familiar with the operation and execution of running the
Dionex Ion Chromatography system. For a more detailed overview consult the Dionex operations
manual.
6.1 Ion Chromatograph Dionex Model ICS-3000
6.2 Below is an example of IC operating conditions. These may change for future analysis.
Sample loop volume
100uL for Anions & Cations
Analytical Column
Anions:
Dionex, Ion Pac AS18
Cations:
Dionex, Ion Pac CS16
Guard Columns
Anions:
Dionex, Ion Pac AS18
Cations:
Dionex, Ion Pac CG16
Eluents
Anions:
10-45mM Potassium Hydroxide
Cations:
26mM Methanesulfonic Acid
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Eluent flow rates:
Anions:
1.0mL/min
Cations:
1.5mL/min
Data acquisition software: Dionex Chromeleon
6.3 Volumetric flasks
6.4 Mechanical shaker
6.5 Ultrasonic bath
6.6 Nylon filters, Teflon filters or Quartz filters
6.7 Teflon tweezers
6.8 Balance
6.9 PE storage bottles
6.10 Beakers
6.11 Chemicals: All chemicals must be shown to be pure and free from potential interfering artifacts.
This is proven by running LRB, MB etc…
6.11.1 Lithium Hydroxide
6.11.2 Carbonate/bicarbonate
6.11.3 Methanesulfonic Acid
6.11.4 Potassium Hydroxide
6.11.5 Sodium Hydroxide
6.11.6 Nanopure ASTM Type 1 deionized water
7.0 Eluent Generation:
The Dionex system uses manufactured cartridges for the generation of the eluents. This eliminates
errors associated with manual eluent generation. The concentration is programmable through the
Chromeleon software. Methanesulfonic Acid is used for the cation eluent. Potassium hydroxide is used
for the anion eluent. Each cartridge contains 900mL of the appropriate concentrated solution.
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8.0 Calibration &Standardization:
8.1 Use of NIST traceable standards is a must. All volumetrics used must be class A either plastic or
glass.
8.2 The pipettes used for making standards must be of known accuracy.
8.3 All standards must be prepared using Nanopure ASTM Type 1 Deionized water.
8.4 Working and control standards must be recorded and documented throughout the analytical
process.
8.5 All standards will be stored in the refrigerator until ready for use at 4 degrees centigrade.
Anion & Cation Stock Standards:
Ion
Concentration(ppm)
Bromate
1000
Bromide
1000
Chlorate
1000
Chloride
1000
Chlorite
1000
Fluoride
1000
Nitrate
1000
Nitrite
1000
o-Phosphate
1000
Sulfate
1000
Ammonium
500
Calcium
500
Lithium
500
Magnesium
500
Potassium
500
Sodium
500
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8.6 The QCS will be from a different source than the suppliers of the stock solutions. The QCS will be
diluted to fit into the calibration range.
8.7 Working standards will be prepared from standard stocks. Working standards will be valid for 21
days from time of preparation or otherwise noted.
8.8 Cations and Anions will have a minimum of three points and a blank to establish the calibration
curve. More points may be needed to establish linearity for a given anion or cation.
8.9 Once calibrated, each analyte must have a correlation coefficient of 0.995 or greater to establish
linearity.
8.10 Ammonium is expected to be non linear. Ammonium is calibrated using a quadratic equation.
9.0 Sample Collection, Preservation, Shipment, and Storage:
9.1 Filters are collected using differing PCM air samplers (i.e. FRM, PCM1, Coarse FRM, Dichotomous,
and CA Denuder).
9.2 No preservation is necessary (i.e. filters).
9.3 Samples are collected at the end of each sampling period (i.e. daily, 1/3, 1/6) and are shipped/stored
at <4oC prior to analysis (except during equilibration and weighing).
9.4 Samples are stored in appropriate containers and exposed as little as possible during sample
processing.
9.5 Samples that are extracted are analyzed immediately or kept in refrigerator storage for further
analysis.
10.0 Quality Control & Quality Assurance:
QA/QC
Frequency
Acceptance Limits
LRB
One per batch
<MDL, PQL or MRL
LCS/LCD
One per batch
+20%
LCD is sample volume
dependent.
QCS
1 per calibration
+10%
ICV/CCV
1 after calibration curve,
+10%
1 every ten samples
1 at the end of run
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ICB/CCB
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1 after calibration curve,
<MDL, PQL, MRL
1 every ten samples
1 at the end of run
FD
Site specific
RPD < 20%
Analyte concentration has to be greater than 5 * the MDL in
order to quantitate RPD.
MS/MSD
1 per batch
MSD is sample volume
dependent.
100+20%, Spike has to be at least 2 * the analyte concentration
in order to calculate recovery.
10.1 Initial demonstration (ID) of instrument capabilities must be determined prior to analyzing any
samples. This consists of creating and validating MDL’s, linear calibration ranges and the analysis of the
QCS.
10.2 Method detection limits (MDL) are established for every analyte of interest. Spike 7 to 10 filters
with analyte(s) and process thru prep method. Run replicates on calibrated instrument and calculate
MDL’s based on the student’s t value for a 99% confidence level and a standard deviation estimate with
n-1 degrees of freedom. MDL= t * s!
10.2.1 MDL’s should be determined whenever significant instrument repair occurs, once every 6 months
or when a new operator takes over the analysis.
10.2.2 If MDL’s fail initial criteria then a new set will be created and analyzed.
10.3 Linear Range Standards (LRS) should be determined initially, whenever significant instrument repair
occurs, once every 6 months or when a new operator takes over the analysis.
10.3.1 (LRS) Fortify ultra pure water with high concentrations of cations or anions and analyze for
linearity. The analyte values must be +10% of the true value to validate the extrapolated linear
calibration range.
10.4 Quality Control Sample (QCS) is used to verify the calibration curve and meet data quality
objectives. The QCS is run at the beginning of every sequence and must be within +10% of the true value
in order to continue with the analytical run. If the QCS fails then calibration curve is invalid, made up
incorrectly or could be contaminated. If the QCS fails a second time remake the QCS and calibration
curve standards. The QCS should be run after the ICV/CCV.
10.5 Once the initial demonstration is accomplished. The instrument is ready for analysis.
11.0 Filter/(Citric Acid) Denuder extraction:
11.1 Powder less gloves, Lab coats and safety glasses must be worn while performing this procedure.
11.2 Prepare a run log of 20 filters/denuders or less.
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11.3 Gather punches, filters or denuders for preparation from freezer, refrigerator or from ambient
storage.
11.4 Make sure all samples/denuders to be extracted are labeled correctly.
11.5 Record samples/denuders in extraction log notebook (i.e. Date, time, method, analyst, final volume
etc…).
11.6 Using PTFE tweezers carefully take punch or filter out of petri dish and insert into extraction vessel.
Cap and label the vessel. Uncap and add 25mL of ultra pure deionized water to each 50mL extraction
vessel using a plastic volumetric cylinder(polypropylene, Nalgene etc…) or a calibrated high volume
pipette. Repeat this procedure for each punch or filter. Make sure to wipe the tweezers with Kim wipes
before and after each use.
11.6.1 Transfer prepared samples to ultrasonic bath using appropriate racks. Make sure that the water
level in the bath is higher than the level in the extraction vessel.
11.6.2 Sonicate all samples for 60 minutes.
11.6.3 After sonicating, secure caps and place samples in a mechanical shaker for 60 minutes. Remove
samples from mechanical shaker and wipe dry. Refrigerate all samples until ready to analyze.
11.7 Original sample extracts will be refrigerated up to 6 months then discarded.
11.8 The CAD is extracted two times with 10mL of ultrapure deionized water. Uncap the CAD and add
first aliquot of water. Shake, and then pour into amber colored wide mouthed bottle. Add second
aliquot of water to CAD denuder. Shake, and then add to first aliquot in amber colored wide mouthed
bottle. Final extract should be 20mL. Denuder extract is ready for analysis.
11.9 Prepare batch QC alongside samples and denuders (i.e. LRB, LCS anion-cation, LCD if applicable, MS
anion-cation, MSD if applicable, FD etc…).
12.0 Ion Chromatography Analysis:
12.1 Power up the IC modules and open the Chromeleon software on the associated computer.
12.2 Open method and setup eluent reservoirs.
12.3 Setup the piston seal washing system to rinse the Single pump or dual pump. Or Both!
12.4 Start and prime the pumps if necessary.
12.5 Set the pump limits. The high system pressure for the DP/SP is 3000psi and the low system
pressure is 200psi. Pumps will shut down when limits are above 3000psi or below 200psi.
12.6 Start the eluent generator and set the desired concentrations.
12.7 Start the detector compartment and or temperature control (method specific).
12.8 Equilibrate the IC system. Watch the detector signal to monitor the background level. Auto zero if
needed.
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12.9 Observe pump pressure. Should be stable (2000-3000psi).
12.10 Method created and loaded. All set points checked and ready for analysis.
12.11 Load auto sampler with prepared extracts.
12.12 Create sequence and start run.
12.13 Monitor analytical sequence and perform data reduction as needed.
12.14 Make sure all QA/QC is adhered to.
12.15 If any problems occur during run, stop the analysis and recalibrate or perform corrective action
procedures.
13.0 Calculations:
13.1 The Chromeleon software calculates concentrations using linear regression or quadratic equations.
The user can specify what units to use (i.e. ng/L, ng/m3, etc…). Manual calculations will be performed to
validate instrument mathematics.
13.2 The QC samples will be calculated in real-time/and or later submitted for further compliance.
13.3 If sample concentrations exceed the LRS then dilute into range and re-analyze.
13.4 Perform data integration as necessary (baseline drift, poor peak shape, etc…)
14.0 Method Performance:
14.1 Work in progress, LRB, FD, LCS, MS etc…
15.0 Maintenance:
15.1 Check for leaks. If the pump pressure starts to differentiate it’s probably the piston seals are
leaking. Remove pump heads and replace.
15.2 Inspect/fill eluent reservoirs. Check for cleanliness and replace when necessary.
15.3 Empty waste container as needed.
15.4 Fill seal wash reservoir as needed.
15.5 Keep track of the Eluent Generator (EG) cartridge expiration date and remaining lifetime in the EG
control panel. Replace cartridge as necessary.
15.5 Monitor the Detector Chromatography Module (DC) for leaks and spills. Clean area as needed.
Replace the sample loop as needed. The Dionex preventative maintenance kit for (DC) module is P/N
061796. Dionex recommends this annually.
15.6 Check the Thermal Compartment for leaks and spills. Isolate and repair leaks.
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15.7 Check all lines to the IC system daily and check for leaks. Replace any lines that are crimped or
discolored. Sample flow rate is crucial for optimum daily performance.
15.8 The analyst should record all maintenance activity in the instrument log book. Remember to sign
and date each entry and document what was performed.
16.0 Pollution Prevention:
16.1 This procedure uses non toxic chemicals at low concentrations (i.e. dilute salts and acids) so the
pollution factor is very low. To keep pollution at a low level, look for safer (less pollutive) alternative
chemicals to use in future analyses and minimize volume whenever possible.
17.0 Waste Management:
17.1 All reagents, waste solutions and standards are stored in safety storage cabinets. All waste is
characterized before disposal and kept in appropriate waste drums. Hazardous waste should be
disposed of by qualified waste disposal company (i.e. Clean Harbors).
18.0 References:
Dionex manual, ICS-3000 Ion Chromatography System Manual Document No. 065031 Revision 03
September 2006
Method 300.0 “Determination of Inorganic Anions by Ion Chromatography” John D. Pfaff, USEPA
Method D6919-03 “Standard Test Method for Determination of Dissolved Alkali and Alkaline Earth
Cations and Ammonium in Water and Wastewater by Ion Chromatography” ASTM Annual book of
standards, Vol 11.01 September 2003
SOP MLD064 “Standard operating Procedure for the analysis of anions and cations in P.M.2.5 Speciation
Samples by Ion Chromatography” California Air & Resource Board (CARB)
SOP “IC analysis of Ambient Air PM” DEQ state of Oregon, February 2003
Method 300.1 “Determination of Inorganic anions in drinking water by Ion Chromatography” USEPA
1997
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