300.1-1

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
300.1-2

METHOD 300.1

DETERMINATION OF INORGANIC ANIONS IN DRINKING WATER BY ION

CHROMATOGRAPHY

 

1.0 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 1B), 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 1A, 1B 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. 
300.1-3

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. 

2.0 SUMMARY OF METHOD

2.1 A small volume of sample, 10 μL for Part A and 50 μL 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.

3.0 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 of ten

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. 
300.1-4

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

the laboratory. The LFM is analyzed exactly like a sample, and its purpose is to
300.1-5

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

sample aliquot in known amounts before any sample processing procedures are

conducted. It is measured with the same procedures used to measure other sample
300.1-6

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.

4.0 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 IC 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

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
300.1-7

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.

5.0 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
300.1-8

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).

6.0 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 1B 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 μL for Part A anions and 200 μL

for Part B anions in order to attain comparable detection limits. A

four fold increase in injection volume compensates for the four

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-
300.1-9

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 (HDPE), 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.

6.9 Micro beakers, plastic, disposable - used during sample preparation.

7.0 Reagents and Standards
300.1-10

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 (Na CO ) in reagent water and dilute to 2 L. 2 3

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 IC

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 (C10 ) 1000 mg/L: Assuming an exact 80.0 % NaC10 is 2 2

-

amperometrically titrated from technical grade NaC10 (See Sect. 7.3.5.1). 2 

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 (NaClO 2) is not currently

commercially available due to potential explosive instability. 

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 % NaClO 2 using the

iodometric titration procedure (Standard Methods, 19th Ed.,

4500-ClO .C). Following titration, an individual component 2
300.1-11

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 -N) 1000 mg/L: Dissolve 0.6068 g sodium nitrate (NaNO ,

-

3 3

CASRN 7631-99-4) in reagent water and dilute to 100 mL in a volumetric

flask.

 

7.3.8 Nitrite (NO -N) 1000 mg/L: Dissolve 0.4926 g sodium nitrite (NaNO ,

-

2 2

CASRN 7632-00-0) in reagent water and dilute to 100 mL in a volumetric

flask.

 

7.3.9 Phosphate (PO4-P) 1000 mg/L: Dissolve 0.4394 g potassium 3-

dihydrogenphosphate (KH2PO4, CASRN 7778-77-0) in reagent water and

dilute to 100 mL in a volumetric flask. 

 

7.3.10 Sulfate (SO ) 1000 mg/L: Dissolve 0.1814 g potassium sulfate (K SO , 4 2 4

2-

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 4EC. Except for the chlorite standard which is

only stable for two weeks when stored protected from light at 4EC, and

nitrite and phosphate which are only stable for 1 month when stored at 4EC. 

Dilute working standards should be prepared monthly, except those that

contain chlorite, or nitrite and phosphate which should be prepared fresh

daily.

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 (Cl2CHCO2K, CASRN 19559-59-2) in

reagent water and dilute to 100 mL in a volumetric flask. 
300.1-12

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 μg/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.

8.0 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:

PART A : Common Anions

Analyte Preservation Holding Time

Bromide None required 28 days

Chloride None required 28 days

Fluoride None required 28 days

Nitrate-N Cool to 4EC 48 hours

Nitrite-N Cool to 4EC 48 hours 

ortho-Phosphate-P Cool to 4EC 48 hours 

Sulfate Cool to 4EC 28 days 

PART B : Inorganic Disinfection By-products

Analyte Preservation Holding Time
300.1-13

Bromate 50 mg/L EDA 28 days

Bromide None required 28 days

Chlorate 50 mg/L EDA 28 days

Chlorite 50 mg/L EDA, Cool to 4EC 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.

8.7 Degradation of ortho-phosphate has been observed in samples held at room

temperature for over 16 hrs (see table 3A). Therefore, samples to be analyzed for

ortho-phosphate must not be held at room temperature for more than 12 cumulative

hours.

9.0 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.
300.1-14

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. To determine MDL (6)

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:

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.
300.1-15

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 10xMRL 75 - 125 %

10xMRL to highest calibration level 85 - 115 % 

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 115%.

9.3.2.3 The laboratory must use the LRB to assess laboratory performance 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 measurements, new control limits can be calculated using only the most
300.1-16

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(1/2)

PGF = ----------------------- 

 W(1/10)

 where: W(1/2) is the peak width at half height 

W(1/10) 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.

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
300.1-17

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

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 μg/L, the

highest LFM fortified concentration allowed is 25.0 μg/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:

 Cs - C

 R = -------- x 100

 s

where, R = percent recovery.

Cs = fortified sample concentration

C = sample background concentration

s = concentration equivalent of analyte added to sample.
300.1-18

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

SRC

 R = --------- x 100

SFC

where, R = percent recovery.

SRC = Surrogate Recovered Concentration

SFC = Surrogate Fortified Concentration

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 (DBP) dichloroacetic

acid (DCAA) Background levels of this organic DBP are rarely

observed above 50 μg/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
300.1-19

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 percent difference (%Diff) of the initial quantitated

concentration (I ) and duplicate quantitated concentration (D ) C c

using the following formula,

(I - D ) C c

%Diff = -------------- X 100

 ([I + D ]/2) C c

9.4.3.2 Duplicate analysis acceptance criteria

Concentration range %Diff Limits

MRL to 10xMRL ± 20 %

 10xMRL 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. 

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.

10.0 Calibration and Standardization
300.1-20

10.1 Establish ion chromatographic operating parameters equivalent to those indicated in

Tables 1A or 1B 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.) 

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 μL 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.
300.1-21

10.4 Using a 2 mm column, inject 10 μL (Part A) or 50 μL (Part B) of each calibration

standard. Using a 4 mm column, inject 50 μL (Part A) or 200 μL (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

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 10xMRL 75 - 125 %

10xMRL 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%.
300.1-22

10.5.2 SPECIAL 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.

11.0 Procedure

11.1 Tables 1A and 1B 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 μL 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 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 μm particulate 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 μL (Part A) or 50 μL (Part B) of each sample. 

Using a 4 mm column, inject 40 μL (Part A) or 200 μL (Part B) of each sample. 
300.1-23

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

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.

12.0 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
300.1-24

should be diluted and reanalyzed. Samples with target analytes identified but

quantitated below the concentration established by the lowest calibration standard

cannot be reported since the lowest calibrated concentration is the minimum

reporting limit (MRL).

12.3 Report results for Part A anions in mg/L and for Part B anions in μg/L. 

12.4 Report NO2 as N -

NO3 as N -

HPO4 as P =

Br in mg/L when reported with Part A -

Br in μg/L when reported with Part B -

13.0 METHODS PERFORMANCE

13.1 Tables 1A, 1B, 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 1A). MDLs for the Part B anions were conducted not only in

reagent water but also a simulated high ionic strength water (HIW) on the 2 mm

column (Table 1B) and in reagent water on the 4 mm column (Table 1C). HIW 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.

 13.2 Tables 2A 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 1B, respectively.

13.3 Tables 3A 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.

14.0 POLLUTION PREVENTION

14.1 Pollution prevention encompasses any technique that reduces or eliminates the

quantity or toxicity of waste at the point of generation. Numerous opportunities for

pollution prevention exist in laboratory operation. The EPA has established a

preferred hierarchy of environmental management techniques that places pollution

prevention as the management option of first choice. Whenever feasible, laboratory

personnel should use pollution prevention techniques to address their waste
300.1-25

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. 

15.0 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.
300.1-26

16.0 REFERENCES 

1. "Determination of Inorganic Disinfection By-Products by Ion Chromatography", J.

Pfaff, C. Brockhoff. J. Am. Water Works Assoc., Vol 82, No. 4, pg 192. 

2. Standard Methods for the Examination of Water and Wastewater, Method 4110B,

"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-

ClO 2,C "Amperometric Method I" (for the determination of Chlorine Dioxide), 19th

Edition of Standard Methods (1995). 
300.1-27

17.0 TABLES, DIAGRAMS, FLOWCHARTS AND VALIDATION DATA

TABLE 1A. CHROMATOGRAPHIC CONDITIONS AND MINIMUM DETECTION

LIMITS IN REAGENT WATER FOR THE COMMON ANIONS (PART

A).

MDL DETERMINATION

ANALYTE PEAK # (MIN.) Replicates mg/L (1)

RETENTION TIME mg/L of MDL

Fort Conc, number DI

Fluoride 1 2.53 0.020 7 0.009

Chloride 2 4.67 0.020 7 0.004

Nitrite-N 3 6.01 0.010 7 0.001

Surrogate: DCA 4 7.03

Bromide 5 8.21 0.040 7 0.014

Nitrate-N 6 9.84 0.010 7 0.008

ortho-Phosphate-P 7 11.98 0.040 7 0.019

Sulfate 8 13.49 0.040 7 0.019

Standard Conditions:

Ion Chromatograph: Dionex DX500

Columns : Dionex AG9-HC / AS9-HC, 2 mm

Detector: Suppressed Conductivity Detector, Dionex CD20 

Suppressor: ASRS-I, external source electrolytic mode, 100 mA current

Eluent: 9.0 mM Na2CO3

Eluent Flow: 0.40 mL/min

Sample Loop: 10 μL

System Backpressure: 2800 psi

Background Conductivity: 22 μS

Recommended minimum total analysis time: 25 minutes

(1) See Figure 1
300.1-28

TABLE 1B. CHROMATOGRAPHIC CONDITIONS AND MINIMUM DETECTION LIMITS

IN BOTH REAGENT WATER AND HIGH IONIC STRENGTH WATER FOR

THE INORGANIC DISINFECTION BY-PRODUCTS (PART B).

MDL DETERMINATION

ANALYTE PEAK # TIME μg/L Replica μg/L μg/L (1)

RETENTION Conc, of MDL MDL

(MIN.) tes

Fort number DI HIW(2)

Chlorite 1 3.63 2.00 7 0.89 0.45

Bromate 2 4.19 2.00 7 1.44 1.28

Surrogate: 4 7.28

DCA

Bromide 5 8.48 2.00 7 1.44 2.51

Chlorate 6 9.28 2.00 7 1.31 0.78

Standard Conditions:

Ion Chromatograph: Dionex DX500

Columns : Dionex AG9-HC / AS9-HC, 2 mm

Detector: Suppressed Conductivity Detector, Dionex CD20 

Suppressor: ASRS-I, external source electrolytic mode, 100 mA current

Eluent: 9.0 mM Na2CO3

Eluent Flow: 0.40 mL/min

Sample Loop: 50 μL

System Backpressure: 2800 psi

Background Conductivity: 22 μS

Recommended minimum 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.
300.1-29

TABLE 1C. CHROMATOGRAPHIC CONDITIONS AND MINIMUM DETECTION LIMITS

IN REAGENT WATER FOR THE INORGANIC DISINFECTION BYPRODUCTS USING AN ALTERNATE 4 mm AS9-HC COLUMN (PART B).

MDL DETERMINATION

ANALYTE PEAK # TIME μg/L Replica μg/L

RETENTION Conc, of MDL

(MIN.) tes

Fort number DI

Chlorite 1 4.43 2.00 7 1.44

Bromate 2 5.10 2.00 7 1.32

Surrogate: 4 8.82

DCA

Bromide 5 10.11 2.00 7 0.98

Chlorate 6 10.94 2.00 7 2.55

Standard Conditions:

Ion Chromatograph: Dionex DX500

Columns : Dionex AG9-HC / AS9-HC, 4 mm

Detector: Suppressed Conductivity Detector, Dionex CD20 

Suppressor: ASRS-I, external source electrolytic mode, 300 mA current 

Eluent: 9.0 mM Na2CO3

Eluent Flow: 1.25 mL/min

Sample Loop: 200 μL

System Backpressure: 1900 psi

Background Conductivity: 21 μS

Recommended minimum total analysis time: 25 minutes
300.1-30

TABLE 2A. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE COMMON ANIONS

(PART A).

ANALYTE MATRIX CONC., mg/L REPLC mg/L %REC SD(n-1) %RSD

UNFORT FORT #

MATRIX CONC OF MEAN MEAN

mg/L

Fluoride RW <DL 2.00 9 1.79 89.7 0.02 1.18 (1)

SW 0.139 2.00 9 1.75 80.4 0.01 0.56

GW 0.280 2.00 9 1.97 84.3 0.02 0.85

CDW 0.807 2.00 9 2.59 89.0 0.01 0.46

Chloride RW 0.029 50.0 9 49.4 98.7 0.03 0.10

SW 12.1 50.0 9 58.7 93.3 0.04 0.10

GW 56.6 50.0 9 100. --- 0.22 0.22 (2)

CDW 16.0 50.0 9 64.9 97.8 0.11 0.16

Nitrite-N RW <DL 1.00 9 0.851 85.1 0.00 0.51

SW <DL 1.00 9 0.780 78.0 0.00 0.40

GW 0.013 1.00 9 0.879 86.6 0.01 0.77

CDW <DL 1.00 9 0.720 72.0 0.00 0.55

Bromide RW <DL 0.500 9 0.480 96.1 0.00 0.92

SW 0.028 0.500 9 0.469 88.1 0.00 0.94

GW 0.153 0.500 9 0.634 96.3 0.00 0.52

CDW <DL 0.500 9 0.431 86.2 0.01 1.28

Nitrate-N RW <DL 10.0 9 9.50 95.0 0.01 0.14

SW 2.12 10.0 9 10.9 87.7 0.03 0.30

GW 0.016 10.0 9 9.64 96.3 0.03 0.27

CDW 1.64 10.0 9 10.9 92.4 0.04 0.41

Phosphate-P RW <DL 10.0 9 9.62 96.2 0.01 0.14

SW <DL 10.0 9 8.70 87.0 0.02 0.18

GW <DL 10.0 9 6.12 61.2 0.28 4.66

CDW <DL 10.0 9 9.15 91.5 0.04 0.42

Sulfate RW <DL 50.0 9 44.8 89.5 0.05 0.11

SW 47.8 50.0 9 92.1 88.6 0.21 0.23

GW 105 50.0 9 154 --- 0.60 0.39 (2)

CDW 57.8 50.0 9 105 --- 0.33 0.32 (2)

Surrogate: RW ---- 5.00 9 5.12 102.3 0.50 0.49

SW ---- 5.00 9 5.09 102.3 1.12 1.09

GW ---- 5.00 9 5.16 101.8 0.67 0.66

CDW ---- 5.00 9 5.17 103.1 1.36 1.32

RW = Reagent Water GW = Ground Water

SW = Surface Water CDW = chlorine dioxide treated finished drinking water 

(1) <DL indicates less than minimum detection limit.

(2) Not calculated since amount fortified was less than unfortified native matrix concentration (See

9.4.1.1.).
300.1-31

TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS (PART B).

ANALYTE MATRIX μg/L μg/L REPLC μg/L %REC SD(n-1) %RSD

UNFORT FORT #

CONC. CONC OF MEAN MEAN

Chlorite RW <DL 100 9 96.2 96.2 0.95 0.99 (1)

500 9 523 105 3.13 0.60

HIW <DL 100 9 102 102 2.19 2.15

500 9 520 104 3.64 0.70

SW <DL 100 9 91.4 91.4 1.22 1.33

500 9 495 99.0 7.54 1.52

GW <DL 100 9 92.9 92.9 1.65 1.77

500 9 490 98.1 3.40 0.69

ClW <DL 100 9 87.4 87.4 0.59 0.68

500 9 485 97.1 6.36 1.31

CDW 292 100 9 396 --- 1.64 0.41 (2)

500 9 811 104 4.00 0.49

O3W <DL 100 9 84.4 84.4 0.46 0.54

500 9 481 96.1 3.24 0.67

Bromate RW <DL 5.00 9 5.04 101 0.45 8.86

25.0 9 26.5 106 1.71 6.47

HIW <DL 5.00 9 4.88 97.5 0.95 19.5

25.0 9 25.6 102 1.37 5.37

SW <DL 5.00 9 4.46 89.2 0.58 13.0

25.0 9 26.3 105 1.10 4.18

GW <DL 5.00 9 5.10 102 0.50 9.75

25.0 9 22.2 88.9 1.29 5.81

ClW <DL 5.00 9 4.63 92.6 0.77 16.7

25.0 9 25.1 100 1.64 6.55

CDW <DL 5.00 9 4.14 82.7 0.62 15.1

25.0 9 25.1 101 1.28 5.09

O3W 1.45 5.00 9 5.49 80.9 0.61 11.1

25.0 9 24.1 90.6 1.13 4.69

RW = Reagent Water GW = Groundwater

HIW = High Ionic strength Water ClW = Chlorinated drinking water 

[see note (2) in Table 1B] CDW = Chlorine dioxide treated drinking water

SW = Surface Water O3W = Ozonated drinking water

(1) <DL indicates less than minimum detection limit.

(2) Not calculated since amount fortified was less than unfortified native matrix concentration (See

9.4.1.1.).
300.1-32

TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS (PART B) (contd.).

ANALYTE MATRIX μg/L μg/L REPLC μg/L %REC SD(n-1) %RSD

UNFORT FORT #

CONC. CONC OF MEAN MEAN

Bromide RW <DL 20.0 9 20.9 104 0.80 3.82 (1)

100 9 107 107 0.60 0.56

HIW 3.24 20.0 9 21.8 92.5 0.79 3.63

100 9 105 102 1.05 1

SW 31.0 20.0 9 51.3 --- 0.97 1.9 (2)

100 9 140. 109 1.88 1.35

GW 151 20.0 9 172 --- 0.78 0.45 (2)

100 9 265 --- 2.18 0.82 (2)

ClW 16.3 20.0 9 39.3 115 0.64 1.62

100 9 125 109 2.00 1.6

CDW 11.5 20.0 9 34.4 115 0.76 2.22

100 9 125 113 1.24 0.99

O3W 39.8 20.0 9 65.4 --- 128 3.67 5.61 (2)

100 9 153 113 1.00 0.65

Chlorate RW <DL 100 9 98.3 98.3 0.80 0.82

500 9 520 104 4.15 0.8

HIW <DL 100 9 86.1 86.1 1.47 1.7

500 9 502 100. 4.52 0.9

SW 3.18 100 9 102 98.3 1.57 1.55

500 9 513 102 7.11 1.39

GW <DL 100 9 93.5 93.5 2.00 2.14

500 9 510 102 3.84 0.75

ClW 34.4 100 9 136 102 1.01 0.74

500 9 549 103 3.11 0.57

CDW 121 100 9 223 --- 102 3.20 1.44 (2)

500 9 651 106 3.50 0.54

O3W 6.15 100 9 106 100 1.20 1.13

500 9 523 103 2.45 0.47

RW = Reagent Water GW = Groundwater

HIW = High Ionic strength Water ClW = Chlorinated drinking water 

[see note (2) in Table 1B] CDW = Chlorine dioxide treated drinking water

SW = Surface Water O3W = Ozonated drinking water

(1) <DL indicates less than minimum detection limit.

(2) Not calculated since amount fortified was less than unfortified native matrix concentration (See

9.4.1.1.).
300.1-33

TABLE 2B. SINGLE-OPERATOR PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS (PART B)(contd.).

ANALYTE MATRIX mg/L REPLC mg/L %REC SD(n-1) %RSD

FORT #

CONC OF MEAN MEAN

Surrogate: DCA RW 5.00 9 5.11 102 0.93 0.91

(see NOTE below) 4.98 99.5 0.69 0.69

HIW 5.00 9 5.00 100 0.79 0.79

4.96 99.2 1.76 1.78

SW 5.00 9 4.95 98.9 0.70 0.7

4.99 99.8 1.60 1.61

GW 5.00 9 5.12 102 0.50 0.49

5.13 103 0.50 0.49

ClW 5.00 9 5.15 103 1.73 1.68

5.13 103 1.12 1.09

CDW 5.00 9 5.01 100 1.02 1.02

5.04 101 1.08 1.07

O3W 5.00 9 4.99 99.8 0.70 0.7

5.11 101 0.53 0.52

RW = Reagent Water GW = Groundwater

HIW = High Ionic strength Water ClW = Chlorinated drinking water 

[see note (2) in Table 1B] CDW = Chlorine dioxide treated drinking water

SW = Surface 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.
300.1-34

TABLE 3A. STABILITY STUDY RESULTS FOR THE COMMON ANIONS (PART A).

ANALYTE Preservative Matrix mg/L mg/L

UNFORT FORT Analyte % Recovery

CONC. CONC Day Day Day See

0 14 28 Note

Fluoride None RW <DL 2.00 89.8 88.3 88.4

SW 0.140 2.00 79.9 80.2 80.0

GW 0.280 2.00 84.7 87.8 87.0

CDW 0.929 2.00 82.9 83.6 81.6

Chloride None RW <DL 50.0 98.8 99.1 98.1

SW 12.0 50.0 93.4 93.5 92.8

GW 56.6 50.0 87.6 87.6 86.5

CDW 16.0 50.0 97.9 98.4 97.8

Nitrite-N None RW <DL 1.00 85.2 85.5 83.6

SW <DL 1.00 77.8 76.6 11.9 (1)

GW <DL 1.00 88.2 85.4 56.1 (1)

CDW <DL 1.00 71.9 71.7 73.9 (2)

Bromide None RW <DL 0.500 95.5 97.0 96.2

SW 0.028 0.500 87.5 88.3 86.7

GW 0.153 0.500 96.9 96.0 96.1

CDW <DL 0.500 85.7 87.1 89.2 (2)

Nitrate-N None RW <DL 10.0 94.9 94.7 94.2

SW 2.12 10.0 87.6 87.0 88.7

GW <DL 10.0 96.5 96.5 95.5

CDW 1.64 10.0 92.3 93.3 91.9

Phosphate-P None RW <DL 10.0 96.3 95.8 95.2

SW <DL 10.0 86.9 86.4 85.1

GW <DL 10.0 62.8 93.1 89.5 (3)

CDW <DL 10.0 91.6 91.4 90.8

Sulfate None RW <DL 50.0 89.6 89.3 89.1

SW 47.8 50.0 89.0 89.0 88.1

GW 105 50.0 97.5 97.3 96.5

CDW 57.8 50.0 94.3 94.9 93.8

NOTES:

(1) Degradation apparent.

(2) Analyte recovery will be adversely effected by reactions with free chlorine.

(3) Phosphate recovery on day 0 is believed to have been adversely effected by biological degradation

since the sample sat in the autosampler for 18 hrs prior to analysis
300.1-35

TABLE 3B STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION BY-PRODUCTS 

(PART B).

ANALYTE Preservative Matrix μg/L μg/L

UNFORT FORT Analyte % Recovery

CONC. CONC Day Day Day Day See

0 3 10 30 Note

Chlorite None RW <DL 500 99.8 100 104 94.3

HIW <DL 500 99.3 98.5 106 89.3

SW <DL 500 92 88.5 82.3 75.1 (1)

GW <DL 500 93.9 94.5 96.1 91.7

ClW <DL 500 93.7 NA 90.3 84.7 (2,3) (1

CDW 286 500 98.6 101 91.7 77.5 (1,3)

O3W <DL 500 10 NA 82.5 90.5 (2)

Chlorite EDA RW <DL 500 101 101 104 95.3

HIW <DL 500 98.4 98.7 104 95.4

SW <DL 500 98.3 97.3 97.8 92.7

GW <DL 500 97.7 97.1 97.5 92.6

ClW <DL 500 98.9 NA 96.9 92.6 (2)

CDW 297 500 103 107 102 94.5

O3W <DL 500 105 NA 96.3 91.9 (2)

Bromate None RW <DL 25.0 93.6 94.1 110 96.1

HIW <DL 25.0 100 86.0 105 87.7

SW <DL 25.0 98.7 95.1 105 102

GW <DL 25.0 79.4 92.4 77.8 82.2

ClW <DL 25.0 102 NA 101 103 (2)

CDW <DL 25.0 104 96.8 98.9 92.1

O3W 2.27 25.0 87.3 NA 84.3 99.9 (2)

Bromate EDA RW <DL 25.0 97.3 95.3 99.5 102

HIW <DL 25.0 86.9 86.1 107 91.2

SW <DL 25.0 100 104 103 94.9

GW <DL 25.0 83.2 101 88.4 88.3

ClW <DL 25.0 105 NA 101 102 (2)

CDW <DL 25.0 117 97.3 98.1 83.9

O3W 2.32 25.0 92.6 NA 84.5 88.9 (2)

See bottom of next page for explanation of notes
300.1-36

TABLE 3B. STABILITY STUDY RESULTS FOR THE INORGANIC

DISINFECTION BY-PRODUCTS (PART B)(contd.)

ANALYTE Preservative Matrix μg/L μg/L

UNFORT FORT Analyte % Recovery

CONC. CONC Day Day Day Day

0 3 10 30

Bromide None RW <DL 100 99.4 97.2 107 101

HIW <DL 100 102 ?? 105 105

SW 30.6 100 102 ?? 107 99.1

GW 149 100 97.7 ?? 109 100

ClW 4.73 100 8.9 NA 37.1 11.4 (2,3) (1

CDW <DL 100 5.78 ?? 38.8 51.3 (3)

O3W 30.4 100 98.3 NA 120 108 (2)

Bromide EDA RW <DL 100 98.4 ?? 107 100

HIW <DL 100 104 ?? 106 105

SW 30.5 100 99.5 ?? 107 100

GW 149 100 100 ?? 114 97.7

ClW 11.9 100 101 NA 115 97.4 (2,3)

CDW 6.14 100 101 ?? 119 110 (3)

O3W 31.0 100 97.3 NA 122 102 (2)

Chlorate None RW <DL 500 102 ?? 105 97.4

HIW <DL 500 96.5 ?? 101 95.4

SW 5.84 500 99.8 ?? 100 96

GW <DL 500 99.5 ?? 101 99.8

ClW 37.8 500 102 NA 104 98.2 (2)

CDW 125 500 102 ?? 104 99.6

O3W 8.34 500 100 NA 103 97.3 (2)

Chlorate EDA RW <DL 500 104 ?? 103 97.3

HIW <DL 500 97.3 ?? 100 95

SW 6.70 500 99.7 ?? 99.9 95.6

GW <DL 500 102 ?? 101 99.3

ClW 38.2 500 101 NA 102 96.1 (2)

CDW 123 500 102 ?? 105 97.7

O3W 8.62 500 98.4 NA 103 96.4 (2)

NOTES:

(1) Degradation in the unpreserved matrix is apparent.

(2) NA indicates "NOT ANALYZED" 

(3) Analyte recovery will be adversely effected by reactions with free chlorine.
Figure 1. Chromatogram showing separation of the Part A common anions on the AS9-HC column. See Table 1A for

analysis conditions.
Figure 2 Chromatogram showing separation of the Part B inorganic DBPs and bromide on the AS9-HC column. See

Table 1B for analysis conditions.
Figure 3. Chromatogram of the inorganic DBPs and bromide (Part B) during the MDL determination in reagent water. 

See Table 1B for analysis conditions.
Figure 4. Chromatogram of the inorganic DBPs and bromide (Part B) in high ionic strength water (HIW). See Table

1B for analysis conditions.