METHOD 300.1
DETERMINATION OF INORGANIC ANIONS IN DRINKING WATER BY ION
CHROMATOGRAPHY
Revision 1.0
John D. Pfaff (USEPA, ORD, NERL) - Method 300.0, (1993)
Daniel P. Hautman (USEPA, Office of Water) and David J. Munch (USEPA, Office of Water)
Method 300.1, (1997)
NATIONAL EXPOSURE RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
300.1-1
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METHOD 300.1
DETERMINATION OF INORGANIC ANIONS IN DRINKING WATER
BY ION CHROMATOGRAPHY
1. SCOPE AND APPLICATION
1.1 This method covers the determination of the following inorganic anions in reagent
water, surface water, ground water, and finished drinking water. As a result of
different specified injection volumes (See conditions in Tables 1A and IB), these
anions are divided between the common anions listed in Part A and the inorganic
disinfection by-products listed in Part B. These different injection volumes are
required in order to compensate for the relative concentrations of these anions in
drinking water and maintain good chromatographic peak shape throughout the
expected dynamic range of the detector. Bromide is included in both Part A, due to
its importance as a common anion, as well as Part B due to its critical role as a
disinfection by-product precursor.
PART A.-- Common Anions
Bromide Nitrite
Chloride ortho-Phosphate-P
Fluoride Sulfate
Nitrate
PART B. Inorganic Disinfection By-products
Bromate Chlorite
Bromide Chlorate
1.2 The single laboratory Method Detection Limits (MDL, defined in Sect. 3.11) for the
above analytes are listed in Tables 1 A, IB and 1C. The MDL for a specific matrix
may differ from those listed, depending upon the nature of the sample and the specific
instrumentation employed.
1.2.1 In order to achieve comparable detection limits, an ion chromatographic
system must utilize suppressed conductivity detection, be properly
maintained and must be capable of yielding a baseline with no more than 5 nS
noise/drift per minute of monitored response over the background
conductivity.
1.3 This method is recommended for use only by or under the supervision of analysts
experienced in the use of ion chromatography and in the interpretation of the
resulting ion chromatograms.
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1.4 When this method is used to analyze unfamiliar samples for any of the above anions,
anion identification should be supported by the use of a fortified sample matrix
covering the anions of interest. The fortification procedure is described in Sect.
9.4.1.
1.5 Users of the method data should state the data-quality objectives prior to analysis.
Users of the method must demonstrate the ability to generate acceptable results with
this method, using the procedures described in Sect. 9.0.
1.6 Bromide and nitrite react with most oxidants employed as disinfectants. The utility
of measuring these anions in treated water should be considered prior to conducting
the analysis.
2. SUMMARY OF METHOD
2.1 A small volume of sample, 10 ^L for Part A and 50 fiL for Part B, is introduced into
an ion chromatograph. The anions of interest are separated and measured, using a
system comprised of a guard column, analytical column, suppressor device, and
conductivity detector.
2.2 The ONLY difference between Parts A and B is the volume of sample analyzed by
the ion chromatographic system. The separator columns and guard columns as well
as eluent conditions are identical.
3. DEFINITIONS
3.1 ANALYSIS BATCH - A group of no more than 20 field samples (Field sample
analyses include only those samples derived from a field sample matrix. These
include the initial and duplicate field samples as well as all Laboratory Fortified
Sample Matrices). The analysis batch must include an Initial Calibration Check
Standard, an End Calibration Check Standard, Laboratory Reagent Blank, and a
Laboratory Fortified Blank. Within an ANALYSIS BATCH, for every group often
field samples, at least one Laboratory Fortified Matrix (LFM) and either a Field
Duplicate, a Laboratory Duplicate or a duplicate of the LFM must be analyzed.
When more than 10 field samples are analyzed, a Continuing Calibration Check
Standard must be analyzed after the tenth field sample analysis.
3.2 CALIBRATION STANDARD (CAL) ~ A solution prepared from the primary
dilution standard solution or stock standard solutions and the surrogate analyte. The
CAL solutions are used to calibrate the instrument response with respect to analyte
concentration.
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3.2.1 INITIAL CALIBRATION STANDARDS ~ A series of CAL solutions used
to initially establish instrument calibration and develop calibration curves for
individual target anions.
3.2.2 INITIAL CALIBRATION CHECK STANDARD - An individual CAL
solution, analyzed initially, prior to any sample analysis, which verifies
previously established calibration curves.
3.2.3 CONTINUING CALIBRATION CHECK STANDARD - An individual
CAL solution which is analyzed after every tenth field sample analyses which
verifies the previously established calibration curves and confirms accurate
analyte quantitation for the previous ten field samples analyzed.
3.2.4 END CALIBRATION CHECK STANDARD - An individual CAL solution
which is analyzed after the last field sample analyses which verifies the
previously established calibration curves and confirms accurate analyte
quantitation for all field samples analyzed since the last continuing calibration
check.
3.3 FIELD DUPLICATES ~ Two separate samples collected at the same time and place
under identical circumstances and treated exactly the same throughout field and
laboratory procedures. Analyses of field duplicates indicate the precision associated
with sample collection, preservation and storage, as well as with laboratory
procedures.
3.4 INSTRUMENT PERFORMANCE CHECK SOLUTION (IPC) - A solution of one
or more method analytes, surrogates, or other test substances used to evaluate the
performance of the instrument system with respect to a defined set of criteria.
3.5 LABORATORY DUPLICATE - Two sample aliquots, taken in the laboratory from
a single sample bottle, and analyzed separately with identical procedures. Analyses
of LD1 and LD2 indicate precision associated specifically with the laboratory
procedures, removing any associated variables attributed by sample collection,
preservation, or storage procedures.
3.6 LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water or
other blank matrices 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.
3.7 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) - An aliquot of an
environmental sample to which known quantities of the method analytes are added in
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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.
3.8 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 surrogates that are used with other
samples. The LRB is used to determine if method analytes or other interferences are
present in the laboratory environment, the reagents, or the apparatus.
3.9 LINEAR CALIBRATION RANGE (LCR) ~ The concentration range over which
the instrument response is linear.
3.10 MATERIAL SAFETY DATA SHEET (MSDS) - Written information provided by
vendors concerning a chemical's toxicity, health hazards, physical properties, fire, and
reactivity data including storage, spill, and handling precautions.
3.11 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.
3.12 MINIMUM REPORTING LEVEL (MRL) -- The minimum concentration that can
be reported for an anion in a sample following analysis. This defined concentration
can be no lower than the concentration of the lowest calibration standard and can
only be used if acceptable quality control criteria for this standard are met.
3.13 PERFORMANCE EVALUATION SAMPLE (PE) -- A certified solution of method
analytes whose concentration is unknown to the analyst. Often, an aliquot of this
solution is added to a known volume of reagent water and analyzed with procedures
used for samples. Results of analyses are used to determine statistically the accuracy
and precision that can be expected when a method is performed by a competent
analyst.
3.14 QUALITY CONTROL SAMPLE (QCS) ~ A solution of method analytes of known
concentrations that 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 laboratory performance with externally
prepared test materials.
3.15 SURROGATE ANALYTE -- An analyte added to a sample, which is unlikely to be
found in any sample at significant concentration, and which is added directly to a
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sample aliquot in known amounts before any sample processing procedures are
conducted. It is measured with the same procedures used to measure other sample
components. The purpose of the surrogate analyte is to monitor method
performance with each sample.
3.16 STOCK STANDARD SOLUTION (SSS) ~ A concentrated solution containing one
or more method analytes prepared in'the laboratory using assayed reference materials
or purchased from a reputable commercial source.
4. INTERFERENCES
4.1 Interferences can be divided into three different categories: direct chromatographic
coelution, where an analyte response is observed at very nearly the same retention
time as the target anion; concentration dependant coelution, which is observed when
the response of higher than typical concentrations of the neighboring peak overlap
into the retention window of the target anion; and, ionic character displacement,
where retention times may significantly shift due to the influence of high ionic
strength matrices (high mineral content or hardness) overloading the exchange sites
in the column and significantly shortening target analyte's retention times.
4.1.1 A direct chromatographic coelution may be solved by changing columns,
eluent strength, modifying the eluent with organic solvents (if compatible
with 1C columns), changing the detection systems, or selective removal of
the interference with pretreatment. Sample dilution will have little to no
effect.
4.1.2 Sample dilution may resolve some of the difficulties if the interference is the
result of either concentration dependant coelution or ionic character
displacement, but it must be clarified that sample dilution will alter your
Minimum Reporting Limit (MRL) by a proportion equivalent to that of
the dilution. Therefore, careful consideration of project objectives should be
given prior to performing such a dilution. An alternative to sample dilution,
may be dilution of the eluent as outlined in 11.9.
4.1.3 Pretreatment cartridges can be effective as a means to eliminate certain
matrix interferences. Prior to using any pretreatment, the analyst should be
aware that all instrument calibration standards must be pretreated in exactly
the same manner as the pretreated unknown field samples. The need for
these cartridges have been greatly reduced with recent advances in high
capacity anion exchange columns.
4.1.3.1 Extreme caution should be exercised in using these pretreatment
cartridges. Artifacts are known to leach from certain cartridges
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which can foul the guard and analytical columns causing loss of
column capacity indicated by shortened retention times and
irreproducible results. Frequently compare your calibration
standard chromatograms to those of the column test
chromatogram (received when the column was purchased) to
insure proper separation and similar response ratios between the
target analytes is observed.
4.2 Method interferences may be caused by contaminants in the reagent water, reagents,
glassware, and other sample processing apparatus that lead to discrete artifacts or
elevated baselines in an ion chromatogram. These interferences can lead to false
positive results for target analytes as well as reduced detection limits as a
consequence of elevated baseline noise.
4.3 Samples that contain particles larger than 0.45 microns and reagent solutions that
contain particles larger than 0.20 microns require filtration to prevent damage to
instrument columns and flow systems.
4.4 Any anion that is only weakly retained by the column may elute in the retention time
window of fluoride and potentially interfere. At concentrations of fluoride above 1.5
mg/L, this interference may not be significant, however, it is the responsibility of the
user to generate precision and accuracy information in each sample matrix.
4.5 Close attention should be given to the potential for carry over peaks from one
analysis which will effect the proper detection of analytes of interest in a second,
subsequent analysis. Normally, the elution of sulfate (retention time of 13.8 min.)
indicates the end of a chromatographic run, but, in the ozonated and chlorine dioxide
matrices, which were included as part of the single operator accuracy and bias study
(See Table 2B), a small response (200 nS baseline rise) was observed for a very late
eluting unknown peak at approximately 23 minutes. Consequently, a run time of 25
minutes is recommended to allow for the proper elution of any potentially interferant
late peaks. It is the responsibility of the user to confirm that no late eluting peaks
have carried over into a subsequent analysis thereby compromising the integrity of
the analytical results.
4.6 Any residual chlorine dioxide present in the sample will result in the formation of
additional chlorite prior to analysis. If any concentration of chlorine dioxide is
suspected in the sample, the sample must be purged with an inert gas (helium, argon
or nitrogen) for approximately five minutes or until no chlorine dioxide remains. This
sparging must be conducted prior to ethylenediamine preservation and at time of
sample collection.
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5. SAFETY
5.1 The toxicity or carcinogenicity of each reagent used in this method have not been
fully established. Each chemical should be regarded as a potential health hazard and
exposure should be as low as reasonably achievable. Cautions are included for
known extremely hazardous materials or procedures.
5.2 Each laboratory is responsible for maintaining a current awareness file of OSHA
regulations regarding the safe handling of the chemicals specified in this method. A
reference file of Material Safety Data Sheets (MSDS) should be made available to all
personnel involved in the chemical analysis. The preparation of a formal safety plan
is also advisable.
5.3 The following chemicals have the potential to be highly toxic or hazardous, consult
MSDS.
5.3.1 Sulfuric acid When used to prepared a 25 mN sulfuric acid regenerant
solution for chemical suppression using a Dionex Anion Micro Membrane
Suppressor (AMMS).
6. EQUIPMENT AND SUPPLIES
6.1 Ion chromatograph Analytical system complete with ion chromatograph and all
required accessories including syringes, analytical columns, compressed gasses and a
conductivity detector.
6.1.1 Anion guard column: Dionex AG9-HC, 2 mm (P/N 52248), or equivalent.
This column functions as a protector of the separator column. If omitted
from the system the retention times will be shorter.
6.1.2 Anion separator column: Dionex AS9-HC column, 2 mm (P/N 52244), or
equivalent. The microbore (2 mm) was selected in the development of this
method as a means to tighten the bromate elution band and thus reduce the
detection limit. An optional column (2 mm or 4 mm) may be used if
comparable resolution of peaks is obtained, and the requirements of Sect. 9.0
can be met. The AS9-HC, 2 mm column using the conditions outlined in
Table 1A and IB produced the separation shown in Figures 1 through 4.
6.1.2.1 If a 4 mm column is employed, the injection volume should be
raised by a factor of four to 40 uL for Part A anions and 200 |^L
for Part B anions in order to attain comparable detection limits. A
four fold increase in injection volume compensates for the four
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fold increase in cross sectional surface area of the 4 mm standard
bore column over the 2 mm microbore column.
6.1.2.2 Comparable results can be attained using the Dionex, AS9-HC, 4
mm column. MDLs for the part B, inorganic disinfection by-
products using this 4 mm column are displayed along with analysis
conditions in Table 1C.
6.1.3 Anion suppressor device: The data presented in this method were generated
using a Dionex Anion Self Regenerating Suppressor (ASRS, P/N 43187).
An equivalent suppressor device may be utilized provided comparable
detection limits are achieved and adequate baseline stability is attained as
measured by a combined baseline drift/noise of no more than 5 nS per minute
over the background conductivity.
6.1.3.1 The ASRS was set to perform electrolytic suppression at a current
setting of 100 mA using an external source DI water mode.
Insufficient baseline stability was observed using the ASRS in
recycle mode.
6.1.4 Detector -- Conductivity cell (Dionex CD20, or equivalent) capable of
providing data as required in Sect. 9.2.
6.2 The Dionex Peaknet Data Chromatography Software was used to generate all the
data in the attached tables. Systems using a strip chart recorder and integrator or
other computer based data system may achieve approximately the same MDL's but
the user should demonstrate this by the procedure outlined in Sect. 9.2.
6.3 Analytical balance, ±0.1 mg sensitivity. Used to accurately weigh target analyte salts
for stock standard preparation.
6.4 Top loading balance, ±10 mg sensitivity. Used to accurately weigh reagents to
prepare eluents.
6.5 Weigh boats, plastic, disposable - for weighing eluent reagents.
6.6 Syringes, plastic, disposable, 10 mL - used during sample preparation.
6.7 Pipets, Pasteur, plastic or glass, disposable, graduated, 5 mL and 10 mL.
6.8 Bottles, high density polyethylene (HOPE), opaque or glass, amber, 30 mL, 125 mL,
250 mL. For sampling and storage of calibration solutions. Opaque or amber due to
the photoreactivity of chlorite anion.
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6.9 Micro beakers, plastic, disposable - used during sample preparation.
7. REAGENTS AND STANDARDS
7.1 Reagent water: Distilled or deionized water, free of the anions of interest. Water
should contain particles no larger than 0.20 microns.
7.2 Eluent solution : Sodium carbonate (CASRN 497-19-8) 9.0 mM. Dissolve 1.91 g
sodium carbonate (NajCOj) in reagent water and dilute to 2 L.
7.2.1 This eluent solution must be purged for 10 minutes with helium prior to use
, to remove dissolved gases which may form micro bubbles in the 1C
compromising system performance and adversely effecting the integrity of
the data.
7.3 Stock standard solutions, 1000 mg/L (1 mg/mL): Stock standard solutions may be
purchased as certified solutions or prepared from ACS reagent grade, potassium or
sodium salts as listed below, for most analytes. Chlorite requires careful
, consideration as outline below in 7.3.5.1.
7.3.1 Bromide (Br) 1000 mg/L: Dissolve 0.1288 g sodium bromide (NaBr,
CASRN 7647-15-6) in reagent water and dilute to 100 mL in a volumetric
flask.
7.3.2 Bromate (BrO3") 1000 mg/L: Dissolve 0.1180 g of sodium bromate
(NaBrO3, CASRN 7789-38-0) in reagent water and dilute to 100 mL in a
volumetric flask.
7.3.3 Chlorate (C103') 1000 mg/L: Dissolve 0.1275 g of sodium chlorate
(NaC103, CASRN 7775-09-9) in reagent water and dilute to 100 mL in a
volumetric flask.
7.3.4 Chloride (Cl') 1000 mg/L: Dissolve 0.1649 g sodium chloride (NaCl,
CASRN 7647-14-5) in reagent water and dilute .to 100 mL in a volumetric
flask.
7.3.5 Chlorite (C102') 1000 mg/L: Assuming an exact 80.0 % NaC102 is
amperometrically titrated from technical grade NaC102(See Sect. 7.3.5.1).
Dissolve 0.1676 g of sodium chlorite (NaC102, CASRN 7758-19-2) in
reagent water and dilute to 100 mL in a volumetric flask.
7.3.5.1 High purity sodium chlorite (NaClO2) is not currently
commercially available due to potential explosive instability.
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Recrystallization of the technical grade (approx. 80%) can be
performed but it is labor intensive and time consuming. The
simplest approach is to determine the exact % NaCIO 2 using the
iodometric titration procedure (Standard Methods, 19th Ed.,
4500-C1O2.C). Following titration, an individual component
standard of chlorite must be analyzed to determine if there is any
significant contamination (greater than 1% of the chlorite weight)
in the technical grade chlorite standard from any of the Part B
components. These contaminants will place a high bias on the
calibration of the other anions if all four Part B components are
mixed in an combined calibration solution. If these other anions
are present as contaminants, a separate chlorite calibration needs
to be performed.
7.3.6 Fluoride (F) 1000 mg/L: Dissolve 0.2210 g sodium fluoride (NaF, CASRN
7681-49-4) in reagent water and dilute to 100 mL in a volumetric flask.
7.3.7 Nitrate (NO"3-N) 1000 mg/L: Dissolve 0.6068 g sodium nitrate (NaNO3,
CASRN 7631-99-4) in reagent water and dilute to 100 mL in a volumetric
flask.
7.3.8 Nitrite (NO'2-N) 1000 mg/L: Dissolve 0.4926 g sodium nitrite (NaNO2,
CASRN 7632-00-0) in reagent water and dilute to 100 mL in a volumetric
flask.
7.3.9 Phosphate (PO43'-P) 1000 mg/L: Dissolve 0.4394 g potassium
dihydrogenphosphate (KH2PO4, CASRN 7778-77-0) in reagent water and
dilute to 100 mL in a volumetric flask.
7.3.10 Sulfate (SO42') 1000 mg/L: Dissolve 0.1814 g potassium sulfate (K2SO4,
CASRN 7778-80-5) in reagent water and dilute to 100 mL in a volumetric
flask.
NOTE: Stability of standards: Stock standards (7.3) for most anions are stable
for at least 6 months when stored at 4°C. Except for the chlorite
standard which is only stable for two weeks when stored protected from
light at 4°C, and nitrite and phosphate which are only stable for 1 month
when stored at 4°C. Dilute working standards should be prepared
monthly, except those that contain chlorite, or nitrite and phosphate
which should be prepared fresh daily.
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7.4 Ethylenediamine (EDA) preservation solution, 100 mg/mL: Dilute 2.8 mL of
ethylenediamine (99%) (CASRN 107-15-3) to 25 mL with reagent water. Prepare
fresh monthly.
7.5 Surrogate Solution: 0.50 mg/mL dichloroacetate (DCA) prepared by dissolving
0.065 g dichloroacetic acid, potassium salt (C12CHCO2K, CASRN 19559-59-2) in
reagent water and dilute to 100 mL in a volumetric flask.
7.5.1 Dichloroacetate is potentially present in treated drinking waters as the
acetate of the organic disinfection by product, dichloroacetic acid (DCAA).
Typical concentrations of DCAA rarely exceed 50 ug/L, which, for this
worst case example, would represent only a five percent increase in the
observed response over the fortified concentration of 1.00 mg/L.
Consequently, the criteria for acceptable recovery (90% to 115%) for the
surrogate is weighted to 115% to allow for this potential background.
7.5.2 Prepare this solution fresh every 3 months or sooner if signs of degradation
are present.
8. SAMPLE COLLECTION. PRESERVATION AND STORAGE
8.1 Samples should be collected in plastic or glass bottles. All bottles must be
thoroughly cleaned and rinsed with reagent water. Volume collected should be
sufficient to insure a representative sample, allow for replicate analysis, if required,
and minimize waste disposal.
8.2 Special sampling requirements and precautions for chlorite.
8.2.1 Sample bottles used for chlorite analysis must be opaque to protect the
sample from light.
8.2.2 When preparing the LFM, be aware that chlorite is an oxidant and may react
with the natural organic matter in an untreated drinking water matrix as a
result of oxidative demand. If untreated water is collected for chlorite
analysis, and subsequently used for the LFM, EDA preservation will not
control this demand and reduced chlorite recoveries may be observed.
8.3 Sample preservation and holding times for the anions that can be determined by this
method are as follows:
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PART A : Common Anions
Analyte
Bromide
Chloride
Fluoride
Nitrate-N
Nitrite-N
ortho-Phosphate-P
Sulfate
Preservation
None required
None required
None required
Cool to 4°C
Cool to 4°C
Cool to 4°C
Cool to 4°C
PART B : Inorganic Disinfection By-products
Analyte Preservation
Bromate 50 mg/L EDA
Bromide None required
Chlorate 50 mg/L EDA
Holding Time
28 days
28 days
28 days
48 hours
48 hours
48 hours
28 days
Holding Time
28 days
28 days
28 days
Chlorite
50 mg/L EDA, Cool to 4 ° C 14 days
8.4 When collecting a sample from a treatment plant employing chlorine dioxide, the
sample must be sparged with an inert gas (helium, argon, nitrogen) prior to addition
of the EDA preservative at time of sample collection:
8.5 All four anions, in Part B, can be analyzed in a sample matrix which has been
preserved with EDA. Add a sufficient volume of the EDA preservation solution
(Sect. 7.4) such that the final concentration is 50 mg/L in the sample. This would be
equivalent to adding 0.5 mL of the EDA preservation solution to 1 L of sample.
8.6 EDA is primarily used as a preservative for chlorite. Chlorite is susceptible to
degradation both through catalytic reactions with dissolved iron salts and reactivity
towards free chlorine which exists as hypochlorous acid/hypochlorite ion in most
drinking water as a residual disinfectant. EDA serves a dual purpose as a
preservative for chlorite by chelating iron as well as any other catalytically destructive
metal cations and removing hypochlorous acid/hypochlorite ion by forming an
organochloroamine. EDA preservation of chlorite also preserves the integrity of
chlorate which can increase in unpreserved samples as a result of chlorite
degradation. EDA also preserves the integrity of bromate concentrations by binding
with hypobromous acid/hypobromite which is an intermediate formed as by-product
of the reaction of either ozone or hypochlorous acid/hypochlorite with bromide ion.
If hypobromous acid/hypobromite is not removed from the matrix further reactions
may form bromate ion.
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8.7 Degradation of ortho-phosphate has been observed in samples held at room
temperature for over 16 hrs (see table 3 A). Therefore, samples to be analyzed for
ortho-phosphate must not be held at room temperature for more than 12 cumulative
hours.
9. QUALITY CONTROL
9.1 Each laboratory using this method is required to operate a formal quality control
(QC) program. The requirements of this program consist of an initial demonstration
of laboratory performance, and subsequent analysis in each analysis batch (Sect. 3.1)
of a Laboratory Reagent Blank, Laboratory Fortified Blank, Instrument Performance
Check Standard, calibration check standards, Laboratory Fortified Sample Matrices
(LFM) and either Field, Laboratory or LFM duplicate sample analyses. This section
details the specific requirements for each of these QC parameters. The laboratory is
required to maintain performance records that define the quality of the data that are
generated.
9.2 INITIAL DEMONSTRATION OF PERFORMANCE
9.2.1 The initial demonstration of performance is used to characterize instrument
performance (determination of accuracy through the analysis of the QCS)
and laboratory performance (determination of MDLs) prior to performing
analyses by this method.
9.2.2 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. If the determined concentrations are not
within ± 15% of the stated values, performance of the determinative step of
the method is unacceptable. The source of the problem must be identified
and corrected before either proceeding with the initial determination of
MDLs or continuing with on-going analyses.
9.2.3 Method Detection Limit (MDL) MDLs must be established for all
analytes, using reagent water (blank) fortified at a concentration of three to
five times the estimated instrument detection limit.(6) To determine MDL
values, take seven replicate aliquots of the fortified reagent water and
process through the entire analytical method over at least three separate
days. Perform all calculations defined in the method and report the
concentration values in the appropriate units. Calculate the MDL as follows:
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MDL = (t) x (S)
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.
9.2.3.1 MDLs should be determined every 6 months, when a new
operator begins work or whenever there is a significant change in
the background, or instrument response.
9.3 ASSESSING LABORATORY PERFORMANCE
9.3.1 Laboratory Reagent Blank (LRB) The laboratory must analyze at least one
LRB with each analysis batch (defined Sect 3.1). Data produced are used to
assess contamination from the laboratory environment. Values that exceed
the MDL indicate laboratory or reagent contamination should be suspected
and corrective actions must be taken before continuing the analysis.
9.3.1.1 If conducting analysis for the Part B anions, EDA must be added
to the LRB at 50 mg/L. By including EDA in the LRB, any bias
as a consequence of the EDA which may be observed in the field
samples, particularly in terms of background contamination, will
be identified.
9.3.2 Laboratory Fortified Blank (LFB) - The LFB should be prepared at
concentrations similar to those expected in the field samples and ideally at the
same concentration used to prepare the LFM. Calculate accuracy as percent
recovery (Sect. 9.4.1.3). If the recovery of any analyte falls outside the
required concentration dependant control limits (Sect! 9.3.2.2), that analyte
is judged out of control, and the source of the problem should be identified
and resolved before continuing analyses.
9.3.2.1 If conducting analysis for the Part B anions, EDA must be added
to the LFB at 50 mg/L. The addition of EDA to all reagent water
prepared calibration and quality control samples is required not as
a preservative but rather as a means to normalize any bias
attributed by the presence of EDA in the field samples.
9.3.2.2 Control Limits for the LRB
Concentration range Percent Recovery Limits
MRL to lOxMRL 75 - 125 %
lOxMRL to highest calibration level 85 - 115 %
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9.3 .2.2. 1 These control limits only apply if the MRL is established
within a factor of 10 times the MDL. Otherwise, the limits
are set at 85% to 1 1 5%.
9.3.2.3 The laboratory must use the LRB to assess laboratory perfor-
mance against the required control limits listed in 9.3.2.2. When
sufficient internal performance data become available (usually a
minimum of 20-30 analyses), optional control limits can be
developed from the percent mean recovery (x) and the standard
deviation (S) of the mean 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 those
listed in 9.3.2.2. After each five to ten new recovery measure-
ments, 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 monitored. These data must be kept on file
and be available for review.
9.3.3 Instrument Performance Check Solution (IPC) The Initial Calibration
Check Standard is to be evaluated as the instrument performance check
solution in order to confirm proper instrument performance. Proper
chromatographic performance must be demonstrated by calculating the Peak
Gaussian Factor (PGF), which is a means to measure peak symmetry and
monitoring retention time drift in the surrogate peak over time. Critically
evaluate the surrogate peak in the initial calibration check standard, and
calculate the PGF as follows,
1.83 x W(l/2)
PGF = ______________________
i VJJL ^~»»«««.»«
where: W( 1 /2) is the peak width at half height
W(l/10) is the peak width at tenth height
9.3.3. 1 The PGF must fall between 0.80 and 1. 15 in order to demonstrate
proper instrument performance.
300.1-16
-------
9.3.3.2 The retention time for the surrogate in the IPC must be closely
monitored on each day of analysis and throughout the lifetime of
the analytical column. Small variations in retention time can be
anticipated when a new solution of eluent is prepared but if shifts
of more than 2% are observed in the surrogate retention time,
some type of instrument problem is present. Potential problems
include improperly prepared eluent, erroneous method parameters
programmed such as flow rate or some other system problem. The
chromatographic profile (elution order) of the target anions
following an ion chromatographic analysis should closely replicate
the profile displayed in the test chromatogram that was shipped
when the column was purchased. As a column ages, it is normal to
see a gradual shift and shortening of retention times, but if after
several years of use, extensive use over less than a year, or use
with harsh samples, this retention time has noticeably shifted to
any less than 80% of the original recorded value, the column may
require cleaning or replacement. Particularly if resolution
problems are beginning to become common between previously
resolved peaks. A laboratory must retain a historic record of
retention times for the surrogate and all the target anions to
provide evidence of an analytical columns vitality.
9.4 ASSESSING ANALYTE RECOVERY AND DATA QUALITY
9.4.1 Laboratory Fortified Sample Matrix (LFM) The laboratory must add a
known amount of analyte to a minimum of 10% of the field samples within
an analysis batch. The LFM sample must be prepared from a sample matrix
which has been analyzed prior to fortification. The analyte concentration
must be high enough to be detected above the original sample and should
adhere to the requirement of 9.4.1.2. It is recommended that the solutions
used to fortify the LFM be prepared from the same stocks used to prepare
the calibration standards and not from external source stocks. This will
remove the bias contributed by an externally prepared stock and focus on any
potential bias introduced by the field sample matrix.
9.4.1.1 If the fortified concentration is less than the observed background
concentration of the unfortified matrix, the recovery should not be
calculated. This is due to the difficulty in calculating accurate
recoveries of the fortified concentration when the native sample
concentration is so high.
9.4.1.2 The LFM should be prepared at concentrations no greater than
five times the highest concentration observed in any field sample.
If no analyte is observed in any field sample, the LFM must be
300.1-17
-------
fortified no greater than five times the lowest calibration level
which as outlined in 12.2 is the minimum reported level (MRL).
For example, if bromate is not detected in any field samples above
the lowest calibrations standard concentration of 5.00 ug/L, the
highest LFM fortified concentration allowed is 25.0 ug/L.
9.4. 1.3 Calculate the percent recovery for each analyte, corrected for
concentrations measured in the unfortified sample. Percent
recovery should be calculated using the following equation:
C8-C
R= --------
where, R = percent recovery.
Cs = fortified sample concentration
C = sample background concentration
s = concentration equivalent of analyte added to
sample.
9.4. 1 .4 Until sufficient data becomes available (usually a minimum of 20
to 30 analysis), assess laboratory performance against recovery
limits of 75 to 125%. When sufficient internal performance data
becomes available develop control limits from percent mean
recovery and the standard deviation of the mean recovery. The
optional control limits must be equal to or better than the required
control limits of 75-125%.
9.4. 1 .5 If the recovery of any analyte falls outside the designated LFM
recovery range and the laboratory performance for that analyte is
shown to be in control (Sect. 9.3), the recovery problem
encountered with the LFM is judged to be either matrix or
solution related, not system related.
9.4.2 SURROGATE RECOVERY -- Calculate the surrogate recovery from all
analyses using the following formula
SFC
where, R = percent recovery.
SRC = Surrogate Recovered Concentration
SFC = Surrogate Fortified Concentration
300.1-18
-------
9.4.2.1 Surrogate recoveries must fall between 90-115% for proper
instrument performance and analyst technique to be verified. The
recovery of the surrogate is slightly bias to 115% to allow for the
potential contribution of trace levels of dichloroacetate as the
halogenated organic disinfection by-product (DBF) dichloroacetic
acid (DCAA) Background levels of this organic DBF are rarely
observed above 50 ug/L (0.05 mg/L) which constitutes only 5%
of the 1.00 mg/L recommended fortified concentration.
9.4.2.2 If the surrogate recovery falls outside the 90-115% recovery
window, a analysis error is evident and sample reanalysis is
required'. Poor recoveries could be the result of imprecise sample
injection or analyst fortification errors.
9.4.3 FIELD OR LABORATORY DUPLICATES » The laboratory must analyze
either a field or a laboratory duplicate for a minimum of 10% of the collected
field samples or at least one with every analysis batch, whichever is greater.
The sample matrix selected for this duplicate analysis must contain
measurable concentrations of the target anions in order to establish the
precision of the analysis set and insure the quality of the data. If none of the
samples within an analysis batch have measurable concentrations, the LFM
should be employed as a laboratory duplicate.
9.4.3.1 Calculate the relative percent difference (RPD) of the initial
quantitated concentration (Ic) and duplicate quantitated
concentration (Dc) using the following formula,
(IC-DC)
RPD = X 100
(Pc + DJ/2)
9.4.3.2 Duplicate analysis acceptance criteria
Concentration ranee %D)ff Limits
MRL to lOxMRL ± 20 %
lOxMRL to highest calibration level ± 10 %
9.4.3.3 If the %Diff fails to meet these criteria, the samples must be
reanalyzed.
9.4.4 Where reference materials are available, they should be analyzed to provide
additional performance data. The analysis of reference samples is a valuable
tool for demonstrating the ability to perform the method acceptably.
300.1-19
-------
9.4.5 In recognition of the rapid advances occurring in chromatography, the
analyst is permitted certain options, such as the use of different columns,
injection volumes, and/or eluents, to improve the separations or lower the
cost of measurements. Each time such modifications to the method are
made, the analyst is required to repeat the procedure in Sect. 9.2 and adhere
to the condition of baseline stability found in Sect. 1.2.1.
9.4.6 It is recommended that the laboratory adopt additional quality assurance
practices for use with this method. The specific practices that are most
productive depend upon the needs of the laboratory and the nature of the
samples. Whenever possible, the laboratory should perform analysis of
quality control check samples and participate in relevant performance
evaluation sample studies.
10. CALIBRATION AND STANDARDIZATION
10.1 Establish ion chromatographic operating parameters equivalent to those indicated in
Tables 1A or IB if employing a 2 mm column, Table 1C if employing a 4 mm
column.
10.2 Estimate the Linear Calibration Range (LCR) ~ The LCR should cover the expected
concentration range of the field samples and should not extend over more than 2
orders of magnitude in concentration (For example, if quantitating nitrate in the
expected range of 1.0 mg/L to 10 mg/L, 2 orders of magnitude would permit the
minimum and maximum calibration standards of 0.20 mg/L and 20 mg/L,
respectively.) The restriction of 2 orders of magnitude is prescribed since beyond this
it is difficult to maintain linearity throughout the entire calibration range.
10.2.1 If quantification is desired over a larger range, then two separate calibration
curves should be prepared.
10.2.2 For an individual calibration curve, a minimum of three calibration standards
are required for a curve that extends over a single order of magnitude and a
minimum of five calibration standards are required if the curve covers two
orders of magnitude. (For example, using the nitrate example cited above in
section 10.2, but in this case limit the curve to extend only from 1.0 mg/L to
10 mg/L or a single order of magnitude. A third standard is required
somewhere in the middle of the range. For the calibration range of 0.20 mg/L
to 20 mg/L, over two orders of magnitude, five calibrations standards should
be employed, one each at the lower and upper concentration ranges and the
other three proportionally divided throughout the middle of the curve.)
300.1-20
-------
10.3 Prepare the calibration standards by carefully adding measured volumes of one or
more stock standards (7.3) to a volumetric flask and diluting to volume with reagent
water.
10.3.1 For the Part B anions, EDA must be added to the calibration standards at 50
mg/L. The addition of EDA to all reagent water prepared calibration and
quality control samples is required not as a preservative but rather as a means
to normalize any bias attributed by the presence of EDA in the field samples.
10.3.2 Prepare a 10.0 mL aliquot of surrogate fortified calibration solution which
can be held for direct manual injection or used to fill an autosampler vial.
Add 20 uL of the surrogate solution (7.5) to a 20 mL disposable plastic
micro beaker. Using a 10.0 mL disposable pipet, place exactly 10.0 mL of
calibration standard into the micro beaker and mix. The calibration standard
is now ready for analysis. The same surrogate solution that has been
employed for the standards should also be used in the section 11.3.2 for the
field samples.
10.4 Using a 2 mm column, inject 10 uL (Part A) or 50 uL (Part B) of each calibration
standard. Using a 4 mm column, inject 50 uL (Part A) or 200 uL (Part B) of each
calibration standard. Tabulate peak area responses against the concentration. The
results are used to prepare calibration curves using a linear least squares fit for each
analyte. Acceptable calibration curves are confirmed after reviewing the curves for
linearity and passing the criteria for the initial calibration check standard in section
10.5.1. Alternately, if the ratio of response to concentration (response factor) is
constant over the LCR (indicated by < 15% relative standard deviation (RSD),
linearity through the origin can be assumed and the average ratio or calibration factor
can be used in place of a calibration curve,
10.4.1 Peak areas are strongly recommended since they have been found to be more
consistent, in terms of quantitation, than peak heights. Peak height can tend
to be suppressed as a result of high levels of common anions in a given
matrix which can compete for exchange sites. Using peak areas, it is the
analyst responsibility to review all chromatograms to insure accurate baseline
integration of target analyte peaks since poorly drawn baselines will more
significantly influence peak areas than peak heights.
10.5 Once the calibration curves have been established they must be verified prior to
conducting any sample analysis using an initial calibration check standard (3.2.2).
This verification must be performed on each analysis day or whenever fresh eluent
has been prepared. A continuing calibration check standard (3.2.3) must be analyzed
after every tenth sample and at the end of the analysis set as an end calibration check
standard (3.2.4). The response for the initial, continuing and end calibration check
must satisfy the criteria listed in 10.5.1. If during the analysis set, the response differs
300.1-21
-------
by more than the calibration verification criteria shown in 10.5.1., or the retention
times shift more than ± 5% from the expected values for any analyte, the test must be
repeated, using fresh calibration standards. If the results are still outside these
criteria, sample analysis must be discontinued, the cause determined and/or in the
case of drift, the instrument recalibrated. All samples following the last acceptable
calibration check standard must be reanalyzed.
10.5.1 Control limits for calibration verification
Concentration range Percent Recovery Limits
MRL to lOxMRL 75 - 125 %
1 OxMRL to highest calibration level 85 - 115 %
10.5.1.1 These control limits only apply if the MRL is established within a
factor of 10 times the MDL. Otherwise, the limits are set at 85%
to 115%.
10.5.2 CALIBRATION VERIFICATION REQUIREMENT FOR PART B
As a mandatory requirement of calibration verification, the laboratory MUST
verify calibration using the lowest calibration standard as the initial
calibration check standard.
10.5.3 After satisfying the requirement of 10.5.2, the levels selected for the other
calibration check standards should be varied between a middle calibration
level and the highest calibration level.
11. PROCEDURE
11.1 Tables 1A and IB summarize the recommended operating conditions for the ion
chromatograph. Included in these tables are estimated retention times that can be
achieved by this method. Other columns, chromatographic conditions, or detectors
may be used if the requirements of Sect. 9.2 are met.
11.2 Check system calibration daily and, if required, recalibrate as described in Sect. 10.
11.3 Sample Preparation
11.3.1 For refrigerated or samples arriving to the laboratory cold, ensure the
samples have come to room temperature prior to conducting sample analysis
by allowing the samples to warm on the bench for at least 1 hour.
11.3.2 Prepare a 10.0 mL aliquot of surrogate fortified sample which can be held for
direct manual injection or used to fill an autosampler vial. Add 20 uL of the
300.1-22
-------
surrogate solution (7.5) to a 20 mL disposable plastic micro beaker. Using a
10.0 mL disposable pipet, place exactly 10.0 mL of sample into the micro
beaker and mix. Sample is now ready for analysis.
11.3.2.1 The less than 1% dilution error introduced by the addition of the
surrogate is considered insignificant.
11.4 Using a Luer lock, plastic 10 mL syringe, withdraw the sample from the micro
beaker and attach a 0.45 \im paniculate filter (demonstrated to be free of ionic
contaminants) directly to the syringe. Filter the sample into an autosampler vial (If
vial is not designed to automatically filter) or manually load the injection loop
injecting a fixed amount of well mixed sample. If using a manually loaded injection
loop, flush the loop thoroughly between sample analysis using sufficient volumes of
each new sample matrix.
11.5 Using a 2 mm column, inject 10 uL (Part A) or 50 uL (Part B) of each sample.
Using a 4 mm column, inject 40 uL (Part A) or 200 uL (Part B) of each sample.
Tabulate peak area responses against the concentration. During this procedure,
retention times must be recorded. Use the same size loop for standards and samples.
Record the resulting peak size in area units. An automated constant volume injection
system may also be used.
11.6 The width of the retention time window used to make identifications should be based
upon measurements of actual retention time variations of standards over the course
of a day. Three times the standard deviation of a retention time can be used to
calculate a suggested window size for each analyte. However, the experience of the
analyst should weigh heavily in the interpretation of chromatograms.
11.7 If the response of a sample analyte exceeds the calibration range, the sample may be
diluted with an appropriate amount of reagent water and reanalyzed. If this is not
possible then three new calibration concentrations must be employed to create a
separate high concentration curve, one standard near the estimated concentration
and the other two bracketing around an interval equivalent to ± 25% the estimated
concentration. The latter procedure involves significantly more time than a simple
sample dilution therefore, it is advisable to collect sufficient sample to allow for
sample dilution or sample reanalysis, if required.
11.8 Shifts in retention time are inversely proportional to concentration. Nitrate,
phosphate and sulfate will exhibit the greatest degree of change, although all anions
can be affected. In some cases this peak migration may produce poor resolution or
make peak identification difficult.
11.9 Should more complete resolution be needed between any two coeluting peaks, the
eluent (7.2) can be diluted. This will spread out the run, however, and will cause late
300.1-23
-------
eluting anions to be retained even longer. The analyst must determine to what extent
the eluent is diluted. This dilution is not be considered a deviation from the method.
If an eluent dilution is performed, section 9.2 must be repeated.
11.9.1 Eluent dilution will reduce the overall response of an anion due to
chromatographic band broadening which will be evident by shortened and
broadened peaks. This will adversely effect the MDLs for each analyte.
12. DATA ANALYSIS AND CALCULATIONS
12.1 Prepare a calibration curve for each analyte by plotting instrument response, as peak
area, against standard concentration. Compute sample concentration by comparing
sample response with the standard curve. If a sample has been diluted, multiply the
response by the appropriate dilution factor.
12.2 Report ONLY those values that fall between the lowest and the highest calibration
standards. Samples with target analyte responses exceeding the highest standard
should be diluted and reanalyzed. Samples with target analytes identified but
quantitated below the concentration established by the lowest calibration standard
should be reported as below the minimum reporting limit (MRL).
12.3 Report results for Part A anions in mg/L and for Part B anions in ug/L.
12.4 Report NO2' asN
NO3" asN
HPO4= as P
Br" in mg/L when reported with Part A
Br" in ug/L when reported with Part B
13. METHODS PERFORMANCE
13.1 Tables 1 A, IB, and 1C give the single laboratory (OW OGWDW TSC-Cincinnati)
retention times, standard conditions and MDL determined for each anion included in
the method. MDLs for the Part A anions were determined in reagent water on the 2
mm column (Table 1 A). MDLs for the Part B anions were conducted not only in
reagent water but also a simulated high ionic strength water (HTW) on the 2 mm
column (Table IB) and in reagent water on the 4 mm column (Table 1C). HTW is
designed to simulate a high ionic strength field sample. It was prepared from reagent
water which was fortified with the common anions of chloride at 100 mg/L,
carbonate at 100 mg/L, nitrate at 10.0 mg/L as nitrogen, phosphate at 10.0 mg/L as
phosphorous, and sulfate at 100 mg/L.
300.1-24
-------
13.2 Tables 2 A and 2B give the single laboratory (OW OGWDW TSC-Cincinnati)
standard deviation for each anion included in the method in a variety of waters for the
standard conditions identified in Table 1A and IB, respectively.
13.3 Tables 3 A and 3B shown stability data for the Part A and B anions, respectively.
Each data point in these tables represent the mean percent recovery following
triplicate analysis. These data were used to formulate the holding times shown in
Sect. 8.3.
14. 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 Quantity of the chemicals purchased should be based on expected usage during its
shelf life and disposal cost of unused material. Actual reagent preparation volumes
should reflect anticipated usage and reagent stability.
14.3 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 Regulations and Science Policy, 1155 16th Street N.W., Washington
D.C. 20036,
(202) 872-4477.
15. WASTE MANAGEMENT
15.1 The Environmental Protection Agency requires that laboratory waste management
practices be conducted consistent with all applicable rules and regulations. Excess
reagents, samples and method process wastes should be characterized and disposed
of in an acceptable manner. 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 waste discharge permit 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 Sect. 14.3.
300.1-25
-------
16. REFERENCES
1. "Determination of Inorganic Disinfection By-Products by Ion Chromatography", J.
Pfaff, C. Brockhoff. J. Am. Waterworks Assoc., Vol 82, No. 4, pg 192.
2. Standard Methods for the Examination of Water and Wastewater, Method 411 OB,
"Anions by Ion Chromatography", 18th Edition of Standard Methods (1992).
3. Dionex, System DX500 Operation and Maintenance Manual, Dionex Corp.,
Sunnyvale, California 94086, 1996.
4. Method Detection Limit (MDL) as described in "Trace Analyses for Wastewater," J.
Glaser, D. Foerst, G. McKee, S. Quave, W. Budde, Environmental Science and
Technology, Vol. 15, Number 12, page 1426, December, 1981.
5. American Society for Testing and Materials. Test Method for Anions in Water by
Chemically-Suppressed Ion Chromatography D4327-91. Annual Book of Standards
Vol 11.01 (1993).
6. Code of Federal Regulations 40, Ch. 1, Pt. 136, Appendix B.
7. Hautman, D.P. & Bolyard, M. Analysis of Oxyhalide Disinfection By-products and
other Anions of Interest in Drinking Water by Ion Chromatography. Jour, of
Chromatog., 602, (1992), 65-74.
8. Standard Methods for the Examination of Water and Wastewater, Method 4500-
C1O 2,C " Amperometric Method I" (for the determination of Chlorine Dioxide), 19th
Edition of Standard Methods (1995).
300.1-26
-------
17. TABLES. DIAGRAMS. FLOWCHARTS AND VALIDATION DATA
TABLE 1A. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION
LIMITS IN REAGENT WATER FOR THE COMMON ANIONS (PART A).
ANALYTE
Fluoride
Chloride
Nitrite-N
Surrogate: DCA
Bromide
Nitrate-N
ortho-Phosphate-P
Sulfate
PEAK # (1>
1
2
3
4
5
6
7
8
RETENTION TIME
(MIN.)
2.53
4.67
6.01
7.03
8.21
9.84
11.98
13.49
MDL
Fort Cone,
mg/L
0.020
0.020
0.010
0.040
0.010
0.040
0.040
1
DETERMINATION
Number
of
Replicates
7
7
7
7
7
7
7
DI
MDL
mg/L
0.009
0.004
0.001
0.014
0.008
0.019
0.019
Standard Conditions:
Ion Chromatograph:
Columns:
Detector:
Suppressor:
Eluent:
Eluent Flow:
Sample Loop:
Dionex DX500
Dionex AG9-HC / AS9-HC, 2 mm
Suppressed Conductivity Detector, Dionex CD20
ASRS-I, external source electrolytic mode, 100 mA current
9.0 mM Na2CO3
0.40 mL/min
10 uL
System Backpressure: 2800 psi
Background Conductivity: 22 uS
Recommended method total analysis time: 25 minutes
(1) See Figure 1
300.1-27
-------
TABLE IB. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION
LIMITS IN BOTH REAGENT WATER AND HIGH IONIC STRENGTH
WATER FOR THE INORGANIC DISINFECTION BY-PRODUCTS
(PART B).
ANALYTE
Chlorite
Bromate
Surrogate:
DCA
Bromide
Chlorate
PEAK # (1)
1
2
4
5
6
.
RETENTION
TIME
(MIN.)
3.63
4.19
7.28
8.48
9.28
MDL DETERMINATION
Fort
Cone,
Hg/L
2.00
2.00
2.00
2.00
Number
of
Replicates
7
7
7
7
DI
MDL
0.89
1.44
1.44
, 1.31
Hr\v<2)
MDL
"g/L
0.45
1.28
2.51
0.78
Standard Conditions:
Ion Chromatograph:
Columns :
Detector:
Suppressor:
Eluent:
Eluent Flow:
Sample Loop:
Dionex DX500
Dionex AG9-HC / AS9-HC, 2 mm
Suppressed Conductivity Detector, Dionex CD20
ASRS-I, external source electrolytic mode, 100 mA current
9.0mMNa2CO3
0.40 mL/min
50 L
System Backpressure: '2800 psi
Background Conductivity: 22 uS
Recommended method total analysis time: 25 minutes
(1) See Figure 2 and 3
(2) HIW indicates High Ionic Strength Water which is a simulated drinking water prepared
from reagent water and fortified with chloride at 100 mg/L, carbonate at 100 mg/L, nitrate
at 10.0 mg/L as nitrogen, phosphate at 10.0 mg/L as phosphorous, and sulfate at 100 mg/L.
300.1-28
-------
TABLE 1C. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION
LIMITS IN REAGENT WATER FOR THE INORGANIC
DISINFECTION BY-PRODUCTS USING AN ALTERNATE 4 mm AS9-
HC COLUMN (PART B).
ANALYTE
Chlorite
Bromate
Surrogate:
DCA
Bromide
Chlorate
PEAK#
1
2
4
5
6
RETENTION
TIME
(MIN.)
4.43
5.10
8.82
10.11
10.94
MDL DETERMINATION
Fort
Cone,
Hg/L
2.00
2.00
2.00
2.00
Number
of
Replicates
7
7
7
7
DI
MDL
ug/L
1.44
1.32
0.98
2.55
Standard Conditions:
Ion Chromatograph:
Columns:
Detector:
Suppressor:
Eluent:
Eluent Flow:
Sample Loop:
Dionex DX500
Dionex AG9-HC / AS9-HC, 4 mm
Suppressed Conductivity Detector, Dionex CD20
ASRS-I, external source electrolytic mode, 300 mA current
1.25 mL/min
200 uL
System Backpressure: 1900 psi
Background Conductivity: 21 uS
Recommended method total analysis time: 25 minutes
300.1-29
-------
TABLE 2A. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE COMMON
ANALYTE
Fluoride
Chloride
Nitrite-N
Bromide
Nitrate-N
Phosphate-P
Sulfate
Surrogate:
ANIONS (PART A).
UNFORT
MATRIX
MATRIX CONC, .
mg/L
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
RW
SW
GW
CDW
-------
TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE
INORGANIC DISINFECTION BY-PRODUCTS (PART B).
Chlorite RW
fflW
SW
GW
C1W
CDW
O3W
Bromate RW
raw
SW
GW
C1W
CDW
O3W
UNFORT
CONC.
ug/L
-------
TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE INORGANIC
DISINFECTION BY-PRODUCTS (PART B) (contd.).
UNFORT FORT #
CONC. CONG OF MEAN MEAN
ANALYTE MATRIX ug/L ug/L REPLC ug/L %REC
RW
fflW
Bromide RW
fflW
SW
GW
C1W
CDW
O3W
Chlorate RW
fflW
.
SW
GW
C1W
CDW
O3W
= Reagent Water
= High Ionic strength
-------
TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE INORGANIC
DISINFECTION BY-PRODUCTS (PART B)(contd.).
ANALYTE
Surrogate: DCA
(see NOTE below)
MATRIX
RW
fflW
SW
GW
C1W
CDW
O3W
FORT
CONC
mg/L
5.00
5.00
5.00
5.00
5.00
5.00
5.00
#
OF
REPLC
9
9
9
9
9
9
9
MEAN
mg/L
5.11
4.98
5.00
4.96
4.95
4.99
5.12
5.13
5.15
5.13
5.01
5.04
4.99
5.11
MEAN
%REC
102
99.5
100
99.2
98.9
99.8
102
103
103
103
100
101
99.8
101
SD(n-l)
0.93
0.69
0.79
1.76
0.70
1.60
0.50
0.50
1.73
1.12
1.02
1.08
0.70
0.53
%RSD
0.91
0.69
0.79
1.78
0.7
1.61
0.49
0.49
1.68
1.09
1.02
1.07
0.7
0.52
RW = Reagent Water
HTW = High Ionic strength Water
[see note (2) in Table IB]
SW= Surface Water
GW = Groundwater
C1W = Chlorinated drinking water
CDW = Chlorine dioxide treated drinking water
O3W = Ozonated drinking water
NOTE:
The surrogate DCA was fortified at 5 mg/L but due to concerns about measuring trace
concentrations of bromide with such high concentration of the neighboring surrogate peak,
the recommended fortified concentration for the surrogate has been reduced to 1.00 mg/L.
300.1-33
-------
TABLE 3A. STABILITY STUDY RESULTS FOR THE COMMON ANIONS (PART A).
ANALYTE
Fluoride
Chloride
Nitrite-N
Bromide
Nitrate-N
Phosphate-P
Sulfate
Preservative Matrix
None RW
SW
GW
CDW
None RW
SW
GW
CDW
None RW
SW
GW
CDW
None RW
SW
GW
CDW
None RW
SW
GW
CDW
None RW
SW
GW
CDW
None RW
SW
GW
CDW
UNFORT
CONC.
mg/L
-------
TABLE 3B STABILITY STUDY RESULTS FOR THE INORGANIC
DISINFECTION BY-
PRODUCTS (PARTB).
ANALYTE
Chlorite
Chlorite
Bromate
Bromate
Preservative Matrix
None RW
raw
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
UNFORT
CONG,
Hg/L
-------
* TABLE 3B. STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION
BY-PRODUCTS (PART B)(contd.)
ANALYTE
Bromide
Bromide
Chlorate
Chlorate
Preservative Matrix
None RW
fflW
SW
GW
C1W
CDW
O3W
EDA RW
fflW
SW
GW
C1W
CDW
O3W
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
UNFORT
CONC.
-------
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