317.0 - 1

EPA Document # EPA 815-B-01-001

METHOD 317.0 DETERMINATION OF INORGANIC OXYHALIDE DISINFECTION

BY-PRODUCTS IN DRINKING WATER USING ION

CHROMATOGRAPHY WITH THE ADDITION OF A

POSTCOLUMN REAGENT FOR TRACE BROMATE ANALYSIS

Revision 2.0

July 2001

Herbert P. Wagner and Barry V. Pepich, IT Corporation and Daniel P. Hautman and

David J. Munch, US EPA, Office of Ground Water and Drinking Water

TECHNICAL SUPPORT CENTER

OFFICE OF GROUND WATER AND DRINKING WATER

U. S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OHIO 45268
317.0 - 2

METHOD 317.0

 DETERMINATION OF INORGANIC OXYHALIDE DISINFECTION BY-PRODUCTS 

IN DRINKING WATER USING ION CHROMATOGRAPHY WITH THE ADDITION

OF A POSTCOLUMN REAGENT FOR TRACE BROMATE ANALYSIS

 

1. SCOPE AND APPLICATION

1.1 This method covers the determination of inorganic oxyhalide disinfection by-product

anions in reagent water, surface water, ground water, and finished drinking water. In

addition, bromide can be accurately determined in source or raw water and it has been

included due to its critical role as a disinfection by-product precursor. Bromide

concentration in finished water can differ significantly between preserved and

unpreserved samples and should not be attempted due to numerous variables which can

influence the concentration. Since this method, prior to the addition of the postcolumn

reagent (PCR), employs the same hardware as EPA Method 300.11

, the analysis of the

common anions (using EPA Method 300.1, Part A1) can be performed using this

instrument setup with the postcolumn hardware attached but “off-line” and with the

appropriate smaller sample loop. 

Inorganic Disinfection By-products by Conductivity Detection

Bromate (report values > 15.0 ug/L) Chlorite

Bromide (source or raw water only) Chlorate

Inorganic Disinfection By-product by Postcolumn UV/VIS Absorbance Detection

Bromate (report values > Minimum Reporting Limit (MRL) to 15.0 ug/L) 

1.2 The single laboratory reagent water Method Detection Limits (MDL, defined in Section

3.14) for the above analytes are listed in Table 1. 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 on the conductivity detector, 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 nanosiemen (nS) noise/drift per minute of monitored response over the

background conductivity. 

1.2.2 In order to achieve acceptable detection limits on the postcolumn absorbance

detector, the postcolumn reagent must be delivered pneumatically and some

form of software signal filtering or smoothing of the absorbance signal from the

absorbance detector must be incorporated.2
317.0 - 3

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. 

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 Section

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 Section 9.0. 

2. SUMMARY OF METHOD

2.1 A volume of sample, approximately 225 :L (see Note), is introduced into an ion

chromatograph (IC). The anions of interest are separated and measured, using a system

comprised of a guard column, analytical column, suppressor device, conductivity

detector, a postcolumn reagent delivery system (pneumatically controlled), a heated

postcolumn reaction coil, and a ultraviolet/visible (UV/VIS) absorbance detector.2,3

NOTE: A 225 uL sample loop can be made using approximately 111 cm (44 inches)

of 0.02 inch i.d. PEEK tubing. Larger injection loops may be employed.4

The volume should be verified to be within 5% by weighing the sample loop

empty, filling the loop with deionized water and re-weighing the loop

assuming the density of water is 1 mg/uL. 

3. DEFINITIONS

3.1 ANALYSIS BATCH – A sequence of samples, which are analyzed within a 30 hour

period and include no more than 20 field samples. An analysis batch must also include

all required QC samples, which do not contribute to the maximum field sample total of

20. The required QC samples include:

• Laboratory Reagent Blank (LRB)

• Initial Calibration Check Standard (ICCS)

• Laboratory Fortified Blank (LFB)

• Continuing Calibration Check Standard (CCCS), when the batch contains more than

10 field samples

• End Calibration Check Standard (ECCS) 

• Laboratory Fortified Matrix (LFM) 

• Either a Field Duplicate (FD), a Laboratory Duplicate (LD) or a duplicate of the LFM

3.2 CALIBRATION STANDARD (CAL) – A solution prepared from the primary dilution

standard solution(s) or stock standard solutions and the surrogate analyte. The CAL
317.0 - 4

solutions are used to calibrate the instrument response with respect to analyte

concentration. 

3.3 INITIAL CALIBRATION STANDARDS – A series of CAL solutions (either

individual or combined target analytes) used to initially establish instrument calibration

and develop calibration curves for individual target anions (Section 10.2).

3.4 INITIAL CALIBRATION CHECK STANDARD (ICCS) – A CAL solution, (either

individual or combined target analytes) which is analyzed initially, prior to any field

sample analyses, which verifies previously established calibration curves. The

concentration for the initial calibration check standard MUST be at or below the MRL

(Section 3.15) level which is also the level of the lowest calibration standard (Section

10.3.1).

3.5 CONTINUING CALIBRATION CHECK STANDARDS (CCCS) – A CAL solution

(either individual or combined target analytes) 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. The

concentration for the continuing calibration check standards should be either at a

middle calibration level or at the highest calibration level (Section 10.3.2).

3.6 END CALIBRATION CHECK STANDARD (ECCS) – A CAL solution (either

individual or combined target analytes) which is analyzed after the last field sample

analysis which verifies the previously established calibration curves and confirms

accurate analyte quantitation for all field samples analyzed since the last continuing

calibration check. The end calibration check standard should be either the middle or

high level continuing calibration check standard (Section 10.3.2). 

3.7 FIELD DUPLICATES (FD) – Two separate field samples collected at the same time

and place under identical circumstances and handled 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. 

3.8 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.

3.9 LABORATORY DUPLICATE (LD) – Two sample aliquots, taken in the laboratory

from a single field sample bottle, and analyzed separately with identical procedures. 

Analysis of the initial sample (IC

) and the duplicate sample [(DC

) Section 9.4.3.1]

indicate precision associated specifically with the laboratory procedures by removing

variation contributed from sample collection, preservation and storage procedures.
317.0 - 5

3.10 LABORATORY FORTIFIED BLANK (LFB) – An aliquot of reagent water or other

blank matrix 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.

3.11 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) – An aliquot of an

environmental field 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

determine whether the field sample matrix contributes bias to the analytical result. The

background concentrations of the analytes in the field sample matrix must be

determined in a separate, unfortified aliquot and the measured values in the LFM

corrected for background concentrations.

3.12 LABORATORY REAGENT BLANK (LRB) – An aliquot of reagent water or other

blank matrix that is handled 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.

3.13 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.

3.14 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.5

3.15 MINIMUM REPORTING LEVEL (MRL) – The minimum concentration that can be

reported as a quantitated value for a target analyte 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 the ICCS are met.

3.16 PROFICIENCY TESTING (PT) or PERFORMANCE EVALUATION (PE) SAMPLE

– A certified solution of method analytes whose concentration is unknown to the

analyst. Frequently, an aliquot of this solution is added to a known volume of reagent

water and analyzed with procedures used for samples. Often, results of these analyses

are used as part of a laboratory certification program to objectively determine the

capabilities of a laboratory to achieve high quality results.

3.17 QUALITY CONTROL SAMPLE (QCS) – A solution of method analytes of known

concentrations that 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.
317.0 - 6

3.18 SURROGATE ANALYTE – An analyte added to all samples, standards, blanks, etc.,

which is unlikely to be found at a significant concentration, and which is added directly

in a known amount before any sample processing procedures are conducted (except in

the procedure for the removal of chlorite as described is Section 11.1.4). 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.

3.19 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 on 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. 

The analyst must verify that these changes do not induce any negative affects on

method performance by repeating and passing all the QC criteria as described in

Section 9.

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 Section 11.2.6. 

4.1.3 Pretreatment cartridges can be effective as a means to eliminate certain matrix

interferences. With any proposed pretreatment, the analyst must verify that

target analyte(s) are not affected by monitoring recovery after pretreatment. 

With advances in analytical separator column technology which employ higher

capacity anion exchange resins, the need for these cartridges has been greatly

reduced.
317.0 - 7

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 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 or subsequent

analysis. Normally, in this analysis, the elution of sulfate (retention time of 17.5 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, a

small response (200 nS baseline rise) was observed for a very late eluting unknown

peak following the response for sulfate. 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.

4.5 Any residual chlorine dioxide present in the sample will result in the formation of

additional chlorite prior to analysis. If residual chlorine dioxide is suspected in the

sample, the sample must be purged with an inert gas (helium, argon or nitrogen) for

approximately five minutes. This sparging must be conducted prior to ethylenediamine

preservation and at the time of sample collection.

4.6 The presence of chlorite can interfere with the quantitation of low concentrations of

bromate on the postcolumn UV/VIS absorbance detector. In order to accurately

quantify bromate concentrations in the range 0.5 - 15.0 :g/L in this postcolumn system,

the excess chlorite must be removed prior to analysis as outlined in Section 11.1.4. 

5. SAFETY

5.1 The toxicity or carcinogenicity of each reagent used in this method have not been fully

established although the postcolumn reagent o-dianisidine, is listed as a potential

human carcinogen. 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 Occupational

Safety and Health Administration (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. 
317.0 - 8

The preparation of a formal safety plan is also advisable. Additional references on

laboratory safety are available.6-9

5.3 The following chemicals have the potential to be highly toxic or hazardous, consult

MSDS.

5.3.1 Sulfuric acid – used to prepared a 25 mN sulfuric acid regenerant solution for

chemical suppression using a Dionex Anion Micro Membrane Suppressor

(AMMS) and for pretreatment for chlorite removal (Section 11.1.4)

5.3.2 Nitric acid – used to prepare the postcolumn reagent.

5.3.3 o-dianisidine [3, 3'- dimethoxybenzidine dihydrochloride (ODA)] – used as the

postcolumn reagent.

6. EQUIPMENT AND SUPPLIES

6.1 Ion chromatograph – Analytical system complete with ion chromatographic pump and

all required accessories including syringes, analytical columns, compressed gasses,

suppressor, conductivity detector, mixing “tee”, postcolumn reagent delivery system, 

reaction coil, reaction coil heater, UV/VIS absorbance detector (Figure 1) and a PC

based data acquisition and control system.

NOTE: Because of its acidic nature and high salt content, the PCR MUST be flushed

from the reaction coil upon completion of the final analysis and prevented from

draining through the reaction coil by gravity once the system is shut down. This can be

accomplished either manually or by incorporating a column switching valve in

combination with a flush and close method in the schedule. 

6.1.1 Anion guard column – Dionex AG9-HC 4 mm (P/N 51791), 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, 4 mm (P/N 51786), or

equivalent (see Note). The AS9-HC, 4 mm column using the conditions outlined

in Table 1 produced the separations shown in Figures 2 and 3.

NOTE: The use of 2 mm columns is not recommended. A 50 uL sample loop

would be required with the 2 mm columns. This reduced injection volume

would decrease the “on-column” bromate and negatively affect PCR reactivity

and the subsequent absorbance response. As well, the 2 mm columns require a

flow rate approximately 4 times less than the 4 mm columns. At the lower flow

rates, band broading may become an issue and it would be difficult, if not

impossible, to accurately maintain the appropriate reduced flow rate for the

PCR.
317.0 - 9

6.1.3 Anion suppressor device – The data presented in this method were generated

using a Dionex Anion Self Regenerating Suppressor (4 mm ASRS, P/N 46081). 

An equivalent suppressor device may be utilized provided comparable

conductivity 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. The suppressor must be able to

withstand approximately 80 - 120 psi back pressure which results from

connecting the postcolumn hardware to the eluent out side of the suppressor.

6.1.3.1 The ASRS was set to perform electrolytic suppression at a current

setting of 100 mA using the external water mode. Insufficient baseline

stability was observed on the conductivity detector using the ASRS in

recycle mode.

6.1.3.2 This method was developed as a multiple component procedure

employing both suppressed conductivity and postcolumn UV/VIS

absorbance detectors in series. If a laboratory is exclusively interested

in monitoring trace bromate using the PCR and the UV/VIS

absorbance detector, the suppressor may not be required. The

performance data presented within this method for the PCR and

UV/VIS absorbance detector, is based upon a suppressed mobile phase

system. A laboratory must generate comparable data as a result of a

complete IDC (Section 9.2) in order to demonstrate comparability of a

non suppressed system.

6.1.4 Detector – Conductivity cell (Dionex CD20, or equivalent) capable of providing

data as required in Section 9.2.

6.1.5 Detector – Absorbance detector (Dionex AD20 or equivalent with 10 mm cell

pathlength, equipped with a tungsten source bulb, or equivalent and capable of

measuring absorbance at 450 nm) capable of providing data as required in

Section 9.2.

6.1.6 Postcolumn reagent delivery system (Dionex PC-10, or equivalent),

pneumatically delivers the postcolumn reagent to mixing tee. The pressure

settings will need to be established on an individual basis for each specific

instrument configuration and at a level which yields the prescribed PCR flow

rates. 

6.1.7 Reaction Coil, 500 uL internal volume, knitted, potted or configured to fit

securely in the postcolumn reaction coil heater. (Dionex P/N 39349, or

equivalent).
317.0 - 10

6.1.8 Postcolumn Reaction Coil Heater, capable of maintaining a temperature of up to

80°C. (Dionex PCH-2, or equivalent).

6.2 Data System – The Dionex Peaknet Data Chromatography Software was used to

generate all the data in the attached tables. Other computer based data systems may

achieve approximately the same MDLs but the user must demonstrate this by the

procedure outlined in Section 9.2. 

6.3 Analytical balance – Used to accurately weigh target analyte salts for stock standard

preparation (±0.1 mg sensitivity).

6.4 Top loading balance – Used to accurately weigh reagents to prepare eluents (±10 mg

sensitivity).

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, used for sample collection and storage of calibration solutions. Opaque or

amber bottles are required due to the photoreactivity of the chlorite anion.

6.9 Micro beakers – Plastic, disposable - used during sample preparation.

6.10 Particulate filters – Gelman ion chromatography Acrodisc 0.45 micron (PN 4485)

syringe filters or equivalent. These cartridges are used to remove particulates and 

[Fe(OH)3(s)] which is formed during the oxidation-reduction reaction between Fe (II)

and ClO2

-

. 

6.11 Hydrogen cartridges – Dionex OnGuard-H cartridges (PN 039596) or equivalent. 

These cartridges are conditioned according to the manufacturer’s directions and are

used to protect the analytical column and the suppressor membrane by removing excess

ferrous iron [Fe (II)]. The ferrous iron is added to field samples to reduce chlorite

levels prior to analysis of chlorine dioxide disinfected water samples.

7. REAGENTS AND STANDARDS

7.1 Reagent water – Distilled or deionized water 18 M S or better, 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 (Na2CO3) in reagent water and dilute to 2 L.
317.0 - 11

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. 

Alternatively, an in-line degas apparatus may be employed.

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 outlined below in Section 7.3.4.1.

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 (C1O3

-

) 1000 mg/L – Dissolve 0.1275 g of sodium chlorate (NaC1O3,

CASRN 7775-09-9) in reagent water and dilute to 100 mL in a volumetric flask. 

 

7.3.4 Chlorite (C1O2

-

) 1000 mg/L – If the amperometric titration of the technical

grade sodium chlorite (NaC1O2

), specified in 7.3.4.1, had indicated the purity of

the salt to be 80.0 % NaC1O2, the analyst would dissolve 0.1676 g of sodium

chlorite (NaC1O2

, CASRN 7758-19-2) in reagent water and dilute to 100 mL in

a volumetric flask.

7.3.4.1 High purity sodium chlorite (NaClO 2) is not currently commercially

available due to its 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 purity of the NaClO 2 using the iodometric titration

procedure.10 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) from chlorate,

bromate or bromide (as other method target anions) in the technical

grade chlorite standard. 

NOTE: Stability of standards – Stock standards (Section 7.3) for most

anions are stable for at least 6 months when refrigerated at <6oC. The

chlorite standard is only stable for two weeks when stored refrigerated

at <6oC and protected from light. Dilute working standards should be

prepared monthly, except those that contain chlorite, which must be

prepared every two weeks or sooner if signs of degradation are

indicated by repeated QC failure.
317.0 - 12

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) – Prepare by dissolving 0.065 g

dichloroacetic acid, potassium salt (Cl2CHCO2K, CASRN 19559-59-2) in reagent water

and diluting 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 :g/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

indicated by the repeated failure of the surrogate QC criteria. 

7.5.3 If the analyst is exclusively interested in monitoring trace bromate using the

PCR and the UV/VIS absorbance detector, the surrogate may be omitted since it

only yields a signal on the conductivity detector. If the surrogate is removed,

the laboratory must adhere to the alternate QC requirements found in Section

9.3.3.3 in order to monitor and demonstrate proper instrument performance.

7.6 Postcolumn reagent – The postcolumn reagent is prepared by adding 40 mL of 70%

redistilled nitric acid (purity as 99.999+%, Aldrich, Cat. No. 22,571-1, Milwaukee, WI,

or equivalent) to approximately 300 mL reagent water (see Note 1) in a well rinsed 500

mL volumetric flask (see Note 2) and adding 2.5 grams of ACS reagent grade KBr

(Sigma, Cat. No. P-5912, St. Louis, MO, or equivalent). Two-hundred-and-fifty

milligrams of purified grade o-dianisidine, dihydrochloride salt [(ODA), (Sigma, Cat.

No. D-3252, or equivalent)] are dissolved, with stirring, in 100 mL methanol

(Spectrophotometric grade, Sigma, Cat. No. M-3641, St. Louis MO, or equivalent). 

After dissolution, the o-dianisidine solution is added to the nitric acid/KBr solution and

diluted to volume with reagent water. The reagent is stable for 24 hours and should be

prepared fresh daily prior to analysis. 

7.6.1 The purity of all reagents employed in the preparation of the postcolumn reagent

is critical. Some commercial manufacturers/suppliers of laboratory chemicals

sell inferior grades of o-dianisidine dihydrochloride. ONLY the purified grade

of this reagent is acceptable (see Notes 3 and 4). The purified ODA

dihydrochloride salt is a white, fine powder.
317.0 - 13

NOTE 1: For selected lots of ODA, the method sensitivity monitored by the

UV-vis detector may be increased by as much as 2-fold if the reagent water used

to prepare the ODA PCR is purged with helium for 30 minutes prior to

preparing the ODA solution. 

NOTE 2: All glassware used to prepare the postcolumn reagent must be

thoroughly rinsed with reagent water prior to use. A champagne or light amber

coloration of the PCR reagent may be evident when freshly prepared. Over

several hours, this slight coloration will fade. Consequently, the PCR must be

prepared in advance and allowed to sit until it is clear, for a minimum of 4 hours

(preferably overnight) prior to use. Occasionally, no matter how well all the

glassware used to prepare the postcolumn reagent is rinsed, a darkly colored

solution (oxidized ODA) may result. These solutions MUST be discarded. For

this reason, it is recommended that the PCR be made in a series of 500 mL lots

with dedicated glassware. The clear solution should be filtered using a 0.45

micron membrane to remove particulates before use.

NOTE 3: Differences in purity as indicated by variations in the physical

appearance of different lots of ODA, even from the same manufacturer can

effect method sensitivity. Although considerably more expensive, a pelletized

form of ODA from one supplier (Sigma, Cat. No. D-9154, St. Louis, MO) has

shown to increase method sensitivity by as much as 2-fold over impure lots of

ODA. Care must be exercised when switching ODA lots to ensure the method

sensitivity is not compromised. 

NOTE 4: The PCR reaction temperature was optimized at 60 °C with the

granular ODA that was available during the original method development. 

Investigation of recent changes in physical appearance/decreased sensitivity and

stability of the ODA PCR indicated that, the method sensitivity with the ODA

currently available, can be dramatically increased (up to 180%) or increased by

up to a factor of 1.8) by increasing the reaction temperature to 80 °C. Use of

temperatures ranging from 60 to 80 °C may be used in this method.

7.7 Ferrous iron [1000 mg/L Fe (II)] solution – Dissolve 0.124 g ferrous sulfate

heptahydrate (FeSO4.7H2O, Sigma, F-7002) in approximately 15 mL reagent water

containing 6 uL concentrated nitric acid and dilute to 25 mL with reagent water in a

volumetric flask (final pH -2). The Fe (II) solution must be prepared fresh every two

days.

7.8 Sulfuric acid (0.5 N) – Dilute 1.4 mL of concentrated sulfuric acid (Fisher Scientific

Certified ACS Plus, A 300-500) to 100 mL.

8. SAMPLE COLLECTION, PRESERVATION AND STORAGE
317.0 - 14

8.1 Samples should be collected in plastic or glass bottles. All bottles must be thoroughly

cleaned and rinsed with reagent water. The volume collected should be sufficient to

insure a representative sample, allow for replicate analysis and laboratory fortified

matrix 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 or amber 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 are as follows:

Analyte Preservation Holding Time

Bromate 50 mg/L EDA, refrigerate at <6oC 28 days

Chlorate 50 mg/L EDA, refrigerate at <6oC 28 days

Chlorite 50 mg/L EDA, refrigerate at <6oC 14 days

Bromide (source/raw water only) EDA permitted, refrigerate at <6oC 28 days

NOTE: Samples for chlorite analysis must arrive at the laboratory within 48 hours of

collection and must be received at 10oC or less.

8.4 When collecting a field sample from a treatment plant employing chlorine dioxide, the

field 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 (bromate > 15.0 ug/L) can be analyzed by conductivity, in a sample

matrix which has been preserved with EDA. Add a sufficient volume of the EDA

preservation solution (Section 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 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.11 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 organochloramine. EDA preservation of chlorite also preserves the

integrity of chlorate which can increase in unpreserved samples as a result of chlorite
317.0 - 15

degradation. EDA also preserves the integrity of bromate concentrations by binding

with hypobromous acid/hypobromite ion which is an intermediate formed as a byproduct of the reaction of either ozone or hypochlorous acid/hypochlorite ion with

bromide ion. If hypobromous acid/hypobromite ion is not removed from the matrix,

further reactions may form bromate ion.

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 capability (IDC), and subsequent analysis in each analysis batch (Section 

3.1) of a Laboratory Reagent Blank (LRB), Initial Calibration Check Standard (ICCS),

Laboratory Fortified Blank (LFB), Instrument Performance Check Standard (IPC),

Continuing Calibration Check Standards (CCCS), Laboratory Fortified Sample Matrix

(LFM) and either a Field, Laboratory or LFM duplicate sample analysis. This section

details the specific requirements for each of these QC parameters for both the

conductivity and absorbance detectors used in this application. Although this method

involves both conductivity and absorbance detection, the MDLs and MRLs may differ

but the QC requirements and acceptance criteria are the same for both detectors. The

QC criteria discussed in the following sections are summarized in Section 17, Tables 4

and 5. The laboratory is required to maintain performance records that define the

quality of the data that are generated. 

9.2 INITIAL DEMONSTRATION OF CAPABILITY 

9.2.1 The Initial Demonstration of Capability (IDC) – This is used to characterize

instrument and laboratory performance prior to performing analyses by this

method. The QC requirements for the IDC discussed in the following section

are summarized in Section 17, Table 4.

9.2.2 Initial demonstration of low system background – Section 9.3.1.

9.2.3 Initial Demonstration of Precision (IDP) – For the 4 conductivity detector

analytes, prepare 7 replicate LFBs fortified at a recommended concentration of

20 ug/L. For the absorbance detector, prepare 7 replicate LFBs fortified at a

recommended concentration of 2.0 ug/L bromate. The percent relative standard

deviation (RSD) of the results must be less than 20%.

9.2.4 Initial Demonstration of Accuracy (IDA) – Using the data generated for Section

9.2.3, calculate the average recovery. The average recovery of the replicate

values must be within ± 15% of the true value. 
317.0 - 16

9.2.5 Quality Control Sample (QCS) – After calibration curves have initially been

established or have been re-established, on a quarterly basis or as required to

meet data quality needs, verify both the calibration and acceptable instrument

performance with the preparation and analyses of an external/second source

QCS. If the determined concentrations are not within ± 20% of the stated

values, performance of the method is unacceptable. The source of the problem

must be identified and corrected before proceeding with the IDC.

9.2.6 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.4

 To determine MDL values, take seven

replicate aliquots of the fortified reagent water and process through the entire

analytical method. The replicates must be prepared and analyzed over three

days. 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], and

S =standard deviation of the replicate analyses.

9.2.6.1 MDLs should be periodically verified, but MUST be initially

determined when a new operator begins work or whenever there is a

significant change in the background, or instrument response.

NOTE: Do not subtract blank values when performing MDL

calculations.

9.2.7 Minimum Reporting Level (MRL) – The MRL is the threshold concentration of

an analyte that a laboratory can expect to accurately quantitate in an unknown

sample. The MRL should be established at an analyte concentration either

greater than three times the MDL or at a concentration which would yield a

response greater than a signal to noise ratio of five. Setting the MRL too low

may cause repeated QC failure upon analysis of the ICCS. Although the lowest

calibration standard may be below the MRL, the MRL must never be

established at a concentration lower than the lowest calibration standard.

9.3 ASSESSING LABORATORY PERFORMANCE 

9.3.1 Laboratory Reagent Blank (LRB) – The laboratory must analyze at least one

LRB with each analysis batch (Section 3.1). Data produced are used to assess
317.0 - 17

contamination from the laboratory environment. Values that exceed 1⁄2 the MRL

indicate a laboratory or reagent contamination is present. If a method analyte is

observed in the LRB it must not exceed 1⁄2 the MRL. Analytes that exceed this

level will invalidate the analysis batch for that method analyte in all

corresponding field samples.

9.3.1.1 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.

9.3.1.2 When the PCR method is used for low level bromate analysis on

samples from public water systems (PWSs) which employ chlorine

dioxide disinfection, the matrix must be pretreated to remove the

potentially interferant chlorite anion (Section 11.1.4). When these

types of pretreated samples, or any type of pretreatment is applied to

field samples included as part of an analysis batch, a second LRB must

be prepared, pretreated and analyzed to confirm no background effects

of the pretreatment are present. If the analysis batch contains only

pretreated samples, then only a pretreated LRB is required.

9.3.2 Laboratory Fortified Blank (LFB) – Prepare a secondary dilution stock using the

same stock solutions used to prepare the calibration standards and the LFM

fortification solution. Since calibration solutions are prepared in large volumes

and can be used over an extended period of time, the integrity of the

concentration of the solution used to fortify the LFM is checked by analyzing

the LFB. The recovery of all analytes must fall in the acceptable recovery range,

as indicated below, prior to analyzing samples. If the LRB recovery for an

analysis batch does not meet these recovery criteria the data are considered

invalid, and the source of the problem must be identified and resolved before

continuing with analyses.

LFB Fortified Concentration range LFB Percent Recovery Limits

MRL to 5 x MRL 75 - 125 %

5 x MRL to highest calibration level 85 - 115 % 

9.3.2.1 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.

9.3.3 Instrument Performance Check (IPC) – The Initial Calibration Check Standard

(ICCS) is to be evaluated as the IPC solution in order to confirm proper
317.0 - 18

instrument performance. As specified in Section 10.3.1, this must be done using

the lowest calibration standard or the standard level established as the MRL. 

This analysis confirms the MRL and demonstrates proper chromatographic

performance at the beginning of each analysis batch. Chromatographic

performance is judged 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. If these criteria are not met, corrective action must be

performed prior to analyzing additional samples. Major maintenance like

replacing columns require rerunning the IDC (Section 9.2). 

9.3.3.1 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, and 

W (1

/10) is the peak width at tenth height.

NOTE: Values for W(1⁄2) and W (1

/

10) can be attained through most

data acquisition software.

9.3.3.2 Small variations in retention time can be anticipated when a new

solution of eluent is prepared but if sudden shifts of more than 5% 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 requires

cleaning or replacement; especially if resolution problems are

beginning to become common between previously resolved peaks. A

laboratory should retain a historic record of retention times for the

surrogate and all the target anions to provide evidence of an analytical

columns vitality.
317.0 - 19

9.3.3.3 If a laboratory chooses to monitor exclusively for trace bromate using

PCR and the UV/VIS absorbance detector, and no other analytes are

being monitored on the conductivity detector, the surrogate may be

omitted from the procedure. In this case, no measurement of PGF is

required. However, the laboratory must carefully monitor the bromate

retention time in the ICCS as an alternate to the surrogate retention

time and, in the same manner, adhere to those specifications set forth

in Section 9.3.3.2. During the course of the analysis, bromate retention

times in the CCCS and ECCS must also be closely monitored to be

certain they adhere to the QC requirements set forth in Section

10.3.2.2.

9.4 ASSESSING ANALYTE RECOVERY AND DATA QUALITY

9.4.1 Laboratory Fortified Sample Matrix (LFM) – The laboratory must add a known

amount of each target analyte to a minimum of 5% of the collected field samples

or at least one with every analysis batch, whichever is greater. Additional LFM

requirements, as described in Section 9.4.1.5, apply when the PCR system is

used for low level bromate in chlorine dioxide disinfected waters. For a LFM to

be valid, the target analyte concentrations must be greater than the native level

and must adhere to the requirement outlined in Section 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 The fortified concentration must be equal to or greater than the native

concentration. Fortified samples that exceed the calibration range

must be diluted to be within the linear range. In the event that the

fortified level is less than the observed native level 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 to fortified

concentration ratio is greater than one.

9.4.1.2 The LFM should be prepared at concentrations no greater than ten

times the highest concentration observed in any field sample and

should be varied to reflect the range of concentrations observed in field

samples. If no analytes are observed in any field sample, the LFM

should be fortified near the MRL. 
317.0 - 20

9.4.1.3 Calculate the percent recovery for each target analyte, corrected for

concentrations measured in the unfortified sample. Percent recovery

should be calculated using the following equation:

 (Cs - C)

%REC = ---------- x 100

 s

where, %REC = percent recovery, 

Cs

 = fortified sample concentration,

C = native sample concentration, and

s = concentration equivalent of analyte added to sample.

9.4.1.4 Recoveries may exhibit a matrix dependence. If the recovery of any

analyte falls outside 75 - 125%, and the laboratory’s performance for

all other QC performance criteria are acceptable, the accuracy problem

encountered with the fortified sample is judged to be matrix related,

not system related. The result for that analyte in the unfortified sample

and the LFM must be labeled suspect/matrix to inform the data user

that the result is suspect due to matrix effects. Repeated failure to

meet suggested recovery criteria indicates potential problems with the

procedure and should be investigated. 

9.4.1.5 When the PCR method is used for low level bromate analysis on field

samples from PWSs which employ chlorine dioxide disinfection and

consequently contain chlorite, a LFM must be prepared, exclusively

for trace bromate, for each of these field samples. Initially, the field

sample is analyzed and chlorite, chlorate and bromide levels are

determined. Then, a second aliquot of field sample is pretreated to

remove chlorite, as described in Section 11.1.4, and analyzed to

determine native bromate concentration. A third aliquot of the field

sample then must be fortified with bromate, pretreated as described in

Section 11.1.4 to remove chlorite, and analyzed to assess bromate

recovery from that matrix. This additional QC is required to rule out

matrix effects and to confirm that the laboratory performed the chlorite

removal step (Section 11.1.4.1) appropriately. This LFM should be

fortified with bromate at concentrations close to but greater than the

level determined in the native sample. Recoveries are determined as

described above (Section 9.4.1.3). Samples that fail the LFM percent

recovery criteria of 75 - 125% must be reported as suspect/matrix.

9.4.2 SURROGATE RECOVERY – The surrogate is specific to the conductivity

detector and shows no response on the postcolumn absorbance detector. 
317.0 - 21

Calculate the surrogate recovery for the conductivity detector from all analyses

using the following formula:

 SRC %REC = --------- x 100

 SFC

where, %REC = percent recovery,

SRC = surrogate recovered concentration, and 

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 range

for the surrogate is extended to 115% to allow for the potential

contribution of trace levels of dichloroacetate as a halogenated organic

disinfection by-product (DBP) of dichloroacetic acid (DCAA). 

Background levels of this organic DBP are rarely observed above 50

:g/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,

an analysis error is evident and sample reanalysis is required. Poor

recoveries could be the result of imprecise sample injection or analyst

fortification errors. If the second analysis also fails the recovery

criterion, report all data for that sample as suspect.

9.4.2.3 If a laboratory chooses to monitor exclusively for trace bromate using

PCR and the UV/VIS absorbance detector, and no other analytes are

being monitored on the conductivity detector, the surrogate may be

omitted from the procedure. In this situation, the laboratory MUST

adopt the QC protocol outlined in Section 9.3.3.3.

9.4.3 FIELD OR LABORATORY DUPLICATES – The laboratory must analyze

either a field or a laboratory duplicate for a minimum of 5% 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 repeated as a

laboratory duplicate.

9.4.3.1 Calculate the relative percent difference (RPD) from the mean using

the following formula:
317.0 - 22

(IC - DC)

RPD = -------------- x 100

 ([IC + DC]/2)

where, RPD = relative percent difference

IC = the initial quantitated concentration, and

DC

 = the duplicate quantitated concentration 

9.4.3.2 Duplicate analysis acceptance criteria.

Concentration range RPD Limits

MRL to 5 x MRL ± 20 %

5 x MRL to highest calibration level ± 10 % 

9.4.3.3 If the RPD for any target analyte falls outside the acceptance criteria

(Section 9.4.3.2) and if all other QC performance criteria are met for

that analyte, the result for the sample and duplicate should be labeled

as suspect/matrix to inform the data user that the result is suspect due

to a potential matrix effect, which led to poor precision. This should

not be a chronic problem and if it frequently recurs (>20% of duplicate

analyses), it indicates a problem with the instrument or analyst

technique that must be corrected.

9.4.4 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 Section 9.2 and adhere to the

condition of conductivity baseline stability found in Section 1.2.1. 

9.4.5 It is recommended that the laboratory adopt additional quality assurance (QA)

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 standards and participate in relevant proficiency testing (PT) or

performance evaluation (PE) sample studies.

10. CALIBRATION AND STANDARDIZATION

10.1 Demonstration and documentation of acceptable initial calibration is required prior to

the IDC and before any samples are analyzed, is required intermittently throughout

sample analysis to meet required QC performance criteria outlined in this method and is

summarized in Tables 4 and 5. Initial calibration verification is performed using a QCS

as well as with each analysis batch using an initial, continuing (when more than 10 field
317.0 - 23

samples are analyzed), and end calibration standards. The procedures for establishing

the initial calibration curve are described in Section 10.2. The procedures to verify the 

calibration with each analysis batch is described in Section 10.3. 

10.2 INITIAL CALIBRATION CURVE

10.2.1 Establish ion chromatographic operating parameters equivalent to those

indicated in Table 1 and configured as shown in Figure 1.

10.2.2 Estimate the Linear Calibration Range – The linear concentration range is the

concentration range over which the instrument response is linear. On the

conductivity detector for the four target analytes (chlorite, bromate, bromide and

chlorate) the linear range should cover the expected concentration range of the

field samples and should not extend over more than two orders of magnitude in

concentration. The restriction of two orders of magnitude is prescribed since

beyond this it is difficult to maintain linearity throughout the entire calibration

range. 

10.2.2.1 If quantification is desired over a larger range, then two separate

calibration curves must be prepared. 

10.2.2.2 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. Because high

concentrations of chlorite can interfere with the postcolumn analysis of

low levels of bromate, the conductivity and absorbance detectors must

be calibrated separately. 

10.2.2.3 Since the concentration ranges in actual field samples by conductivity

detection for chlorite, bromide and chlorate are expected to cover two

orders of magnitude, the use of at least five calibration standards in the

range 5 - 500 :g/L is recommended. Bromate concentrations are

expected to be significantly lower. It is suggested that the conductivity

detector be calibrated using at least five bromate calibration standard

levels in the range 5 - 100 :g/L. Additionally, report values for

bromate by conductivity ONLY when they are measured by the PCR

above 15.0 ug/L. The conductivity detector will observe a response for

bromate at concentration below 15.0 ug/L but concentrations between

5.0 and 15.0 ug/L are within the calibrated range for PCR detection

and will reflect far better precision and accuracy. 

10.2.2.4 Although the bromate calibration curve for the absorbance detector
317.0 - 24

extends over less than two orders of magnitude, the use of five

calibration standards, containing only bromate in the range 0.5 - 15.0 

:g/L, is recommended. 

10.2.3 Prepare the calibration standards by carefully adding measured volumes of one

or more stock standards (Section 7.3) to a volumetric flask and diluting to

volume with reagent water. Prior to using mixed standards for calibration, it

must be ensured that the individual calibration standards do not contain any

appreciable concentrations of the other target analytes. 

 

10.2.3.1 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 contributed by the addition of EDA to preserve

the field samples.

10.2.3.2 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. This is done by adding 20 :L of the surrogate

solution (Section 7.5) to a 20 mL disposable plastic micro beaker. 

Next, transfer 10.0 mL of calibration standard into the micro beaker

and mix. These volumes may be adjusted to meet specific laboratory

autosampler volume requirements provided the fortified surrogate

concentration is at the prescribed concentration of 1.0 mg/L. The

calibration standard is now ready for analysis. The same surrogate

solution that has been employed for the standards should also be used

in Section 11.1 for the field samples.

NOTE: This surrogate fortification procedure may be omitted if a

laboratory chooses to monitor exclusively for trace bromate using PCR

and the UV/VIS absorbance detector, and no other analytes are being

monitored on the conductivity detector. In this situation, the

laboratory must adopt the QC protocol outlined in Section 9.3.3.3.

10.2.4 Inject 225 :L of each calibration standard. Increased sensitivity for low level

detection of bromate by PCR can be achieved by increasing the injected sample

volume.4 If the injection volume is increased special operating conditions must

be used to insure proper chromatographic performance.4

10.2.5 Tabulate peak area responses against the concentration for the four target

analytes, the surrogate from the conductivity detector and bromate from the

postcolumn absorbance detector. The results are used to prepare calibration

curves using linear regression analysis for each analyte on the conductivity

detector and using a quadratic regression analysis for bromate on the absorbance
317.0 - 25

detector. 

10.2.5.1 Use of 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 leading to peak broadening. 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.

10.2.6 After establishing or reestablishing calibration curves, the accuracy of this

calibration must be verified through the analysis of a QCS or an externally

prepared second source standard. The QCS should be prepared at a

concentration near the middle of the calibration and is best to be analyzed in

triplicate. As specified in Section 9.2.5, determined concentrations must fall

within ± 15% of the stated values.

10.3 CONTINUING CALIBRATION VERIFICATION – Initial calibrations may be stable

for extended periods of time. Once the calibration curves have been established for

both the conductivity and absorbance detectors, they must be verified for each analysis

batch, prior to conducting any field sample analyses using an Initial Calibration Check

Standard. Continuing Calibration Check Standards and End Calibration Check

Standards are also required as described in the sections below.

10.3.1 INITIAL CALIBRATION CHECK STANDARD (ICCS) – The initial

calibration must be determined to be valid each day prior to analyzing any

samples. Since two detectors are incorporated in this method, this must be

accomplished by using a mixed calibration check standard for the four

conductivity analytes and a separate low level bromate initial calibration check

standard for the absorbance detector. In both cases, the lowest level standard

used to prepare the calibration curve must be used. In cases where the analyst

has chosen to set the MRL above the lowest standard, a standard at a

concentration equal to or below the MRL is acceptable. Percent recovery for the

ICCS must be in the range or 75 - 125% before the analyst is allowed to analyze

samples. 

10.3.2 CONTINUING CALIBRATION CHECK/END CALIBRATION CHECK

STANDARDS (CCCS/ECCS) – Continuing calibration check standards must

be analyzed after every tenth field sample analysis and at the end of the analysis

batch as an end calibration check standard. For the reasons noted above, two

separate continuing and end calibration check standards must be incorporated. 

If more than 10 field samples are included in an analysis batch, the analyst must
317.0 - 26

alternate between the middle and high continuing calibration check standard

levels. 

10.3.2.1 The percent recovery for the CCCS/ECCS must meet the following

criteria:

Concentration range Percent Recovery Limits

MRL to 5 x MRL 75 - 125 %

5 x MRL to highest calibration level 85 - 115 % 

10.3.2.2 If during the analysis batch, the measured concentration on either

detector differs by more than the calibration verification criteria shown

above, or the retention times shift more than ± 2% from the last

acceptable initial or continuing calibration check standard for any

analyte, all samples analyzed after the last acceptable calibration check

standard are considered invalid and must be reanalyzed. The source of

the problem must be identified and resolved before reanalyzing the

samples or continuing with the analyses. 

10.3.2.3 In the case where the end calibration failed to meet performance

criteria, but the initial and middle calibration check standards were

acceptable, the samples bracketed by the acceptable calibration check

standards may be reported. However, all field samples between the

middle and end calibration check standards must be reanalyzed.

11. PROCEDURE

11.1 SAMPLE PREPARATION

11.1.1 For refrigerated or field 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.

11.1.2 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. This is done by

adding 20 :L of the surrogate solution (Section 7.5) to a 20 mL disposable

plastic micro beaker. Next, place a 10.0 mL aliquot of sample into the micro

beaker and mix. These volumes may be adjusted to meet specific laboratory

autosampler volume requirements provided the fortified surrogate concentration

is at the prescribed concentration of 1.0 mg/L. The sample is now ready for

analysis.

NOTE: The less than 1% dilution error introduced by the addition of the
317.0 - 27

surrogate is considered insignificant. In addition, this surrogate fortification

procedure may be omitted if a laboratory chooses to monitor exclusively for

trace bromate using PCR and the UV/VIS absorbance detector, and no other

analytes are being monitored on the conductivity detector. In this situation, the

laboratory must adopt the QC protocol outlined in Section 9.3.3.3.

11.1.3 Using a Luer lock, plastic 10 mL syringe, withdraw the sample from the micro

beaker and attach a 0.45 :m 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 filtered, 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. 

11.1.4 CHLORINE DIOXIDE - TREATED WATERS CONTAINING CHLORITE –

Treatment plants that use chlorine dioxide as part of their treatment process can

produce high levels of chlorite in samples. Since chlorite can interfere with the

postcolumn quantitation of low levels of bromate as described in Section 4.6,

chlorite must be removed from these samples prior to analysis.12 The oxidationreduction reaction between ferrous iron and chlorite13 is used to remove chlorite

without any adverse affects on the bromate concentration.

14 The EDA stabilized

sample is acidified to a pH of 5-6 (verified using pH test strips), ferrous iron

solution is added and allowed to react for 10 minutes. The sample is then

filtered using a 0.45 micron membrane to remove precipitated ferric hydroxide

and the excess soluble iron is removed by passing the filtered sample through a

hydrogen cartridge [a solid phase extraction (SPE) clean-up cartridge in the H+

form, (Section 6.11)], prior to analysis. Prior to using any pretreatment, each lot

of cartridges must be QC checked to insure proper analyte recoveries are

maintained and laboratory reagent blanks are free from interferences. In

addition, consistent lots of reagents, pretreatment cartridges, and membrane

cartridges must be used throughout an entire analysis batch to maintain assured

QC uniformity.

11.1.4.1 Place a 10 mL aliquot of sample in a 20 mL micro beaker and add 35

uL of 0.5 N sulfuric acid (Section 7.8). After mixing, verify the pH is

between 5 and 6 using pH test strips, add 40 uL of ferrous iron solution

(Section 7.7), mix and allow to react for 10 minutes. Filter the

reaction mixture using a 0.45 micron particulate filter (Section 6.10)

attached to a 10 mL syringe into the barrel of a second syringe to

which a pre-conditioned hydrogen cartridge (Section 6.11) is attached. 

Pass the solution through a hydrogen cartridge at a flow rate of

approximately 2 mL per minute. Discard the first 3 mL, and collect an

appropriate volume (depending on autosampler vial size) for analysis. 
317.0 - 28

Add the respective volume of surrogate solution, depending on the

volume collected, and the sample is ready for analysis. 

NOTE: Pretreated samples can be held for no more than 30 hours after

initial pretreatment. If this time has expired, the pretreatment steps

must be repeated on a second aliquot of both the field sample matrix

and the respective LFM.

11.1.4.2 In order to ensure data quality, all samples from PWSs which utilize

chlorine dioxide which have been pretreated to remove chlorite,

MUST also be used to prepare a pretreated LFM specific to trace

bromate. This LFM should be fortified with bromate at concentrations

close to but greater than the level determined in the native sample. 

Initially, the field sample is analyzed and chlorite, chlorate and

bromide levels are determined. Then, a second aliquot of field sample

is pretreated to remove chlorite, as described above and analyzed to

determine native bromate concentrations. A third aliquot of the field

sample then must be fortified with bromate, pretreated to remove

chlorite, and analyzed to assess bromate recovery from that matrix. 

This additional QC is required to rule out matrix effects and to confirm

that the laboratory performed the chlorite removal step appropriately. 

If the bromate recovery falls outside the acceptance range of 75 - 125%

(Section 9.4.1.5), that particular sample should be reported as

suspect/matrix. 

11.1.4.3 Suppressor devices which have had long term exposure to iron cations

may have reduced method performance in other applications, such as

the determination of certain common inorganic anions. If reduced

peak response is observed, particularly for fluoride or phosphate, the

ASRS should be cleaned according to the manufacturer’s

recommendations.

11.2 SAMPLE ANALYSIS

11.2.1 Table 1 summarizes the recommended operating conditions for the ion

chromatograph and delivery of the postcolumn reagent. Included in this table is

estimated retention times that can be achieved by this method. Other columns

or chromatographic conditions may be used if the requirements of Section 9.2

are met. 

11.2.2 Establish a valid initial calibration as described in Section 10.2 and complete the 

IDC (Section 9.2). Check system calibration by analyzing an ICCS (Section

10.3.1) as part of the initial QC for the analysis batch and, if required,

recalibrate as described in Section 10.3. 
317.0 - 29

11.2.3 Inject 225 :L of each sample. Use the same size loop for standards and

samples. An automated constant volume injection system may also be used. 

11.2.3.1 Increased sensitivity for low level detection of bromate by PCR can be

achieved by increasing the injected sample volume.4

 If the injection

volume is increased (Section 10.2.4) special operating conditions must

be used to insure proper chromatographic performance.4

11.2.4 The width of the retention time window used to make identifications should be

based upon measurements of actual retention time variations of standards

measured over several days. Three times the standard deviation of 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. 

11.2.5 If the response of a sample analyte exceeds the calibration range, the sample

must be diluted with an appropriate amount of EDA fortified reagent water and

reanalyzed. If this is not possible then three new calibration concentrations

must be employed to create a separate high concentration calibration curve, one

standard near the estimated concentration and the other two bracketing around

an interval equivalent to approximately ± 25% the estimated concentration. The

latter procedure involves significantly more time than a simple sample dilution

and, therefore, it is advisable to collect sufficient sample to allow for sample

dilution and sample reanalysis, if required.

11.2.6 Should more complete resolution be needed between any two coeluting peaks,

the eluent (Section 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

verify that this dilution does not negatively affect performance by repeating and

passing all the QC criteria in Section 9, and by reestablishing a valid initial

calibration curve (Section 10.2). As a specific precaution, upon dilution of the

carbonate eluent, a peak for bicarbonate may be observed by conductivity within

the retention time window for bromate which will negatively impact the

analysis.

11.2.6.1 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.

11.3 AUTOMATED ANALYSIS WITH METHOD 317.0 

11.3.1 Laboratories conducting analyses on large numbers of samples often prepare
317.0 - 30

large analysis batches that are run in an automated manner. When conducting

automated analyses, careful attention must be paid to all reservoirs to be certain

sufficient volumes are available to sustain extended operation. Laboratories

must ensure that all QC performance criteria are met as described in preceding

sections to ensure their data are of acceptable quality. 

11.3.1.1 Special attention must be made when the PCR reservoir is refilled. 

Since this is a pneumatically driven system, the baseline will require a

minimum of ten minutes to restabilize after the reservoir has been

refilled and the bottle repressurized.

11.3.2 Because this method has two detectors that require independent calibration, 

analysis sequences must be carefully constructed to meet required QC

specifications and frequency (Table 5). To help with this task, an acceptable

sequence for a sample analysis batch, with all the method-required QC, is shown

in Table 6. This schedule is included only as an example of a hypothetical

analysis batch where the analyst desires to collect data using both detectors. 

Within the analysis batch, references to exact concentrations for the ICCS,

CCCS and ECCS are for illustrative purposes only. The analyses for sample

#14 provides an example of the QC requirements for a complete conductivity

and trace bromate PCR analysis of a sample from a PWS employing chlorine

dioxide disinfection. 

11.3.3 Table 6 may be used as a guide when preparing analysis batches. 

12. DATA ANALYSIS AND CALCULATIONS

12.1 Identify the method analytes in the sample chromatogram by comparing the retention

time of the suspected analyte peak to the retention time of a known analyte peak in a

calibration standard. If analyte retention times have shifted (generally towards shorter

times) since the initial calibration, but are still within acceptance criteria and are

reproducible during the analysis batch, the analyst should use the retention time in the

daily calibrations to confirm the presence or absence of target analytes.

12.2 Compute sample concentration using the initial calibration curve generated in Section

10.2. 

12.3 Report ONLY those values that fall between the MRL and the highest calibration

standards. Samples with target analyte responses exceeding the highest standard must

be diluted and reanalyzed. When this is not possible the alternate calibration

procedures described in Section 11.2.5 must be followed. Samples with target analytes

identified but quantitated below the concentration established by the lowest calibration

standard may be reported as present, but below the minimum reporting limit (MRL),

and consequently not quantitated.
317.0 - 31

12.3.1 Report bromate concentrations using the postcolumn UV/VIS absorbance

detector when they fall between the MRL and 15.0 ug/L. When bromate

concentrations exceed 15.0 ug/L, as detected by UV/VIS absorbance, either

report by conductivity, calibrate the postcolumn UV/VIS absorbance detector to

a higher bromate concentration, or dilute the sample.

12.4 Report results in :g/L. 

12.5 Software filtering of the postcolumn UV/VIS absorbance signal is required to improve

the precision of peak measurements, minimize non-random noise and improve peak

appearance. Olympic smoothing (25 points, 5 seconds with 1 iteration) was chosen

using peak area for quantitation because it was determined to have minimal effect on

peak height and/or area.

2,15 The use of alternate smoothing routines is acceptable

providing all QC criteria are met. 

13. METHOD PERFORMANCE

13.1 Table 1 gives the standard conditions, typical retention times and single laboratory

MDLs in reagent water, as determined for each of the inorganic oxyhalide DBPs and

bromide. Included in this table is a comparison of the MDLs determined by

conductivity both with and without the postcolumn UV/VIS absorbance system on-line. 

These data indicate that the postcolumn UV/VIS detector system has no effect on

conductivity detector performance (careful attention must however be paid to insure

backpressure on the suppressor is kept below 120 psi). 

13.2 Table 2 shows the precision and accuracy of the trace bromate measurement, evaluated

on both detectors, at two fortified concentrations, in chlorinated surface water, a

simulated high ionic strength water (HIW) and a simulated high organic (HOW) content

water. The mean bromate recovered concentration (accuracy relative to the fortified

level) and the precision (expressed as %RSD of the replicate analyses) are tabulated. 

The HIW was designed to simulate a high ionic strength field sample and the HOW

designed to simulate a high organic content field sample. The HIW 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.1

 The HOW was prepared from reagent water

fortified with 1.0 mg/L fulvic acid.1

13.3 Table 3 gives the single laboratory standard deviation and precision (% RSD) for each

anion included in the method in a variety of waters for the standard conditions

identified in Table 1.1,2

13.4 Table 3A shows the stability data for the inorganic oxyhalide DBPs. Each data point in

these tables represent the mean percent recovery following triplicate analyses. These
317.0 - 32

data were used to formulate the holding times shown in Section 8.3.1

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 feasiblely 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 Section 14.3.

16. REFERENCES 

1. U.S. EPA Method 300.1. EPA Document number: EPA/600/R-98/118. NTIS number

PB98-169196 INZ.
317.0 - 33

2. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “Analysis of 500 ng/L Levels

of Bromate in Drinking Water by Direct Injection and Suppressed Ion Chromatography

Coupled with a Single, Pneumatically Delivered Postcolumn Reagent.” Journal

Chromatography A, 850 (1999), 119-129.

3. Wagner, H.P., Alig, A.E., Pepich, B.V., Frebis, C.P., Hautman, D.P. and Munch, D.J. “A

Study of Ion Chromatographic Methods for Trace Level Bromate Analysis in Drinking

Water Comparing the Selective Anion Concentration (SAC) Method, U.S. EPA 300.1 and a

Postcolumn Reagent Procedure.” AWWA WQTC Proceedings, 4D-1, San Diego, CA,

(November 1998).

4. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “Performance Evaluation of a

Method for the Determination of Bromate in Drinking Water by Ion Chromatography (EPA

317.0) and validation of EPA Method 324.0 ” Presented at the International Ion

Chromatography Symposium, San Jose, CA, September, 1999. Accepted for publication 

Journal of Chromatography A, (anticipated) June 2000.

5. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L. "Trace Analyses

for Wastewater," Environmental Science and Technology, Vol. 15, Number 12, page 1426,

December, 1981.

6. “OSHA Safety and Health Standards, General Industry,” (29CFR1910). Occupational Safety

and Health Administration, OSHA 2206, (Revised, Jan. 1976).

7. ASTM Annual Book of Standards, Part II, Volume 11.01, D3370-82, “Standard Practice for

Sampling Water,” American Society for Testing and Materials, Philadelphia, PA, 1986.

8. “Carcinogens-Working with Carcinogens,” Publication No. 77-206, Department of Health,

Education, and Welfare, Public Health Service, Center for Disease Control, National

Institute of Occupational Safety and Health, Atlanta, Georgia, August 1977.

9. “Safety In Academic Chemistry Laboratories,” 3rd Edition, American Chemical Society

Publication, Committee on Chemical Safety, Washington, D.C., 1979.

10. 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). 

11. Hautman, D.P. & Bolyard, M. “Analysis of Oxyhalide Disinfection By-products and other

Anions of Interest in Drinking Water by Ion Chromatography.” Journal of Chromatography,

602, (1992 ), 65-74.
317.0 - 34

12. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “The Use of EPA Method

300.1 with the Addition of a Postcolumn Reagent for the Analysis of Ultra Trace Levels of

Bromate in Drinking Water and the Analysis of Bromate in Bottled Waters.” Presented at

Pittcon 99, Orlando FL, paper 1414, (March 1999).

13. Iatrou, A. and Knocke, W.R. Removing Chlorite by the Addition of Ferrous Iron. Journal of

the AWWA, Research and Technology, (November, 1992), 63-68.

14. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “Eliminating the Chlorite

Interference in US Environmental Protection Agency Method 317.0 Permits the Analysis of

Bromate in all Drinking Water Matrices.” Accepted for publication in Journal of 

Chromatography A, (anticipated) Fall 2000.

15. Schibler, J.A. American Laboratory, (December, 1997), 63-64.

16. Dixon, W.J. “Processing Data Outliers.” Biometrics, BIOMA, 9 (No.1):74-89 (1953).
317.0 - 35

17. TABLES, DIAGRAMS, FLOWCHARTS AND VALIDATION DATA

TABLE 1. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION

LIMITS IN REAGENT WATER FOR THE INORGANIC OXYHALIDE

DISINFECTION BY-PRODUCTS AND BROMIDE.

Standard Conditions and Equipment(a):

Ion Chromatograph: Dionex DX500

Sample Loop: 225 :L

Eluent: 9.0 mM Na2CO3

Eluent Flow: 1.3 mL/min

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

Typical System Backpressure: 2300 psi

Suppressor: ASRS-I, external water mode, 100 mA current 

Detectors: Suppressed Conductivity Detector, Dionex CD20

Background Conductivity: 24 :S

Absorbance Detector, Dionex AD20 (10 mm cell path)

Set for absorbance at 450 nm (Tungsten lamp)

Postcolumn Reagent Flow: 0.7 mL/min 

Postcolumn Reactor Coil: knitted, potted for heater, 500 uL internal volume

Postcolumn Heater: 80 °C

Recommended method total analysis time: 25 minutes

Analyte Retention Times and Method Detection Limits (MDLs):

MDL DETERMINATION

Analyte

Retention Time (b)

(min.)

Fortified Conc.

(:g/L)

# of 

Reps.

MDL

(:g/L)

Chlorite(c)

Chlorite(d)

4.20

4.20

2.0

2.0

8

8

0.45

0.89

Bromate(c)

Bromate(d)

Bromate(e)

4.85

4.85

5.35

2.0

2.0

0.50

8

8

7

0.98

0.71

0.12

Surrogate: DCA(d) 8.50

Bromide(c)

Bromide(d)

10.0

10.0

2.0

2.0

8

8

0.54

0.69

Chlorate(c)

Chlorate(d)

11.0

11.0

2.0

2.0

8

8

0.92

0.62

(a) Mention of trade names or commercial products does not constitute endorsement or recommendation

for use. 

(b) Reference to chromatograms in Figure 2 and 3. 

(c) Method 317.0 conductivity detection without PCR online. 

(d) Method 317.0 conductivity detection with PCR online. 

(e) Method 317.0 ONLY bromate by postcolumn UV/VIS absorbance detection.
317.0 - 36

TABLE 2. SINGLE LABORATORY PRECISION IN VARIOUS MATRICES FOR

BROMATE BY CONDUCTIVITY AND ABSORBANCE DETECTION.

PRECISION

Matrix Detection

Fortified

Conc.

(:g/L)

# of Reps.

Mean

(:g/L)

SD

(n-1)

%

RSD

Reagent 

Water

Conductivity 0.50 8 < MRL(a) < MRL

Conductivity 5.0 8 4.8 0.420 8.83

Absorbance 0.50 8 0.50 0.054 10.8

Absorbance 5.0 8 5.4 0.110 2.10

Chlorinated

Drinking Water 

Conductivity 0.50 8 < MRL < MRL

Conductivity 5.0 7

(b) 4.1 0.650 15.7

Absorbance 0.50 8 0.53 0.050 2.77

Absorbance 5.0 8 5.2 0.098 1.87

High Ionic

Water

Conductivity 0.50 8 < MRL < MRL

Conductivity 5.0 8 4.5 0.960 21.4

Absorbance 0.50 8 0.52 0.430 8.20

Absorbance 5.0 8 5.1 0.199 3.90

High 

Organic

Water

Conductivity 0.50 8 < MRL < MRL

Conductivity 5.0 8 5.1 0.199 3.90

Absorbance 0.50 8 0.50 0.044 8.81

Absorbance 5.0 8 5.2 0.014 2.61

(a) <MRL = analyte was not detected at or above the minimum reporting level.

(b) n = 8 one outlier reject using Dixon’s Outlier Test.

16

Standard Conditions: Same as listed in Table 1.
317.0 - 37

TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS AND BROMIDE.1,2

Analyte Matrix

Unfortified

Conc.

(:g/L)

Fortified 

Conc.

(:g/L)

# of 

Reps.

Mean

(:g/L)

Mean

%REC SD(n-1) %RSD

Chlorite RW <MRL(a) 100 9 96.2 96.2 0.95 0.99

500 9 520 105 3.13 0.60

HIW <MRL 100 9 102 102 2.19 2.15

500 9 520 104 3.64 0.70

SW <MRL 100 9 91.4 91.4 1.22 1.33

500 9 500 99.0 7.54 1.52

GW <MRL 100 9 92.9 92.9 1.65 1.77

500 9 490 98.1 3.40 0.69

ClW <MRL 100 9 87.4 87.4 0.59 0.68

500 9 490 97.1 6.36 1.31

CDW 292 100 9 400 NC(b) 1.64 0.41

500 9 810 104 4.00 0.49

O3W <MRL 100 9 84.4 84.4 0.46 0.54

500 9 480 96.1 3.24 0.67

Bromate RW <MRL 5.0 9 5.05 101 0.45 8.86

by 25 9 26.5 106 1.71 6.47

Conductivity HIW <MRL 5.0 9 4.88 97.5 0.95 19.5

25 9 25.5 102 1.37 5.37

SW <MRL 5.0 9 4.46 89.2 0.58 13.0

25 9 26.3 105 1.10 4.18

GW <MRL 5.0 9 5.10 102 0.50 9.75

25 9 22.2 88.9 1.29 5.81

ClW <MRL 5.0 9 4.63 92.6 0.77 16.7

25 9 25.0 100. 1.64 6.55

CDW <MRL 5.0 9 4.14 82.7 0.62 15.1

25 9 25.3 101 1.28 5.09

O3W 1.45 5.0 9 5.50 80.9 0.61 11.1

25 9 24.1 90.6 1.13 4.69

RW = Reagent Water ClW = Chlorinated Drinking Water 

HIW = High Ionic Strength Water CDW = Chlorine Dioxide Treated Drinking Water

SW = Surface Water O3W = Ozonated Drinking Water

GW = Groundwater

(a) <MRL = analyte was not detected at or above the minimum reporting level.

(b) NC = Not calculated since amount fortified was less than unfortified native matrix concentration (Section 

9.4.1.1.).
317.0 - 38

TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS AND BROMIDE (cont.).1,2

Analyte Matrix

Unfortified

Conc.

(:g/L)

Fortified

Conc.

(:g/L)

# of

Reps.

Mean

(:g/L)

Mean

%REC SD(n-1) %RSD

Bromide RW <MRL(a) 20.0 9 20.8 104 0.80 3.82

100 9 110 107 0.60 0.56

HIW 3.2 20.0 9 21.7 92.5 0.79 3.63

100 9 110 102 1.05 1.00

SW 31 20.0 9 51.0 NC(b) 0.97 1.90

100 9 140 109 1.88 1.35

GW 150 20.0 9 170 NC 0.78 0.45

100 9 260 NC 218 0.82

ClW 16 20.0 9 39.0 115 0.64 1.62

100 9 130 109 2.00 1.60

CDW 12 20.0 9 35.0 115 0.76 2.22

100 9 130 113 1.24 0.99

O3W 40. 20.0 9 65.0 NC 3.67 5.61

100 9 150 113 1.00 0.65

Chlorate RW <MRL 100 9 98.3 98.3 0.80 0.82

500 9 520 104 4.15 0.80

HIW <MRL 100 9 86.1 86.1 1.47 1.70

500 9 500 100. 4.52 0.90

SW 3.2 100 9 100 98.3 1.57 1.55

500 9 510 102 7.11 1.39

GW <MRL 100 9 93.5 93.5 2.00 2.14

500 9 510 102 3.84 0.75

ClW 34 100 9 140 102 1.01 0.74

500 9 550 103 3.11 0.57

CDW 120 100 9 220 NC 3.20 1.44

500 9 650 106 3.50 0.54

O3W 6.2 100 9 110 100. 1.20 1.13

500 9 520 103 2.45 0.47

RW = Reagent Water ClW = Chlorinated Drinking Water 

HIW = High Ionic Strength Water CDW = Chlorine Dioxide Treated Drinking Water

SW = Surface Water O3W = Ozonated Drinking Water

GW = Groundwater

(a) <MRL = analyte was not detected at or above the minimum reporting level.

(b) NC = Not calculated since amount fortified was less than unfortified native matrix concentration (Section 

 9.4.1.1.).
317.0 - 39

TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC

DISINFECTION BY-PRODUCTS AND BROMIDE (cont.).1,2

Analyte Matrix

Fortified

Conc.

(mg/L)

# of

Reps.

Mean

(mg/L)

Mean

%REC SD(n-1) %RSD

Surrogate: DCA RW 5.0 9 5.1 102 0.93 0.91

(see Note) 5.0 99.5 0.69 0.69

HIW 5.0 9 5.0 100. 0.79 0.79

5.0 99.2 1.76 1.78

SW 5.0 9 4.9 98.9 0.70 0.7

5.0 99.8 1.60 1.61

GW 5.0 9 5.1 102 0.50 0.49

5.1 103 0.50 0.49

ClW 5.0 9 5.2 103 1.73 1.68

5.1 103 1.12 1.09

CDW 5.0 9 5.0 100. 1.02 1.02

5.0 101 1.08 1.07

O3W 5.0 9 5.0 99.8 0.70 0.7

5.1 101 0.53 0.52

RW = Reagent Water ClW = Chlorinated Drinking Water 

HIW = High Ionic Strength Water CDW = Chlorine Dioxide Treated Drinking Water

SW = Surface Water O3W = Ozonated Drinking Water

GW = Groundwater

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.
317.0 - 40

TABLE 3A. STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION BYPRODUCTS AND BROMIDE.1

Analyte Preservative Matrix

Unfortified

Conc.

(:g/L)

Fortified

Conc.

(:g/L)

Analyte % Recovery

Day

0

Day

3

Day

10

Day

30

See

Note

Chlorite None RW <MRL 500 99.8 100 104 94.3

HIW <MRL 500 99.3 98.5 106 89.3

SW <MRL 500 92.0 88.5 82.3 75.1 (a)

GW <MRL 500 93.9 94.5 96.1 91.7

ClW <MRL 500 93.7 NA(a) 90.3 84.7 (b,c)

CDW 290 500 98.6 101 91.7 77.5 (a,c)

O3W <MRL 500 10.0 NA 82.5 90.5 (b)

Chlorite EDA RW <MRL 500 101 101 104 95.3

HIW <MRL 500 98.4 98.7 104 95.4

SW <MRL 500 98.3 97.3 97.8 92.7

GW <MRL 500 97.7 97.1 97.5 92.6

ClW <MRL 500 98.9 NA 96.9 92.6 (b)

CDW 300 500 103 107 102 94.5

O3W <MRL 500 105 NA 96.3 91.9 (b)

Bromate None RW <MRL 25.0 93.6 94.1 110 96.1

HIW <MRL 25.0 100. 86.0 105 87.7

SW <MRL 25.0 98.7 95.1 105 102

GW <MRL 25.0 79.4 92.4 77.8 82.2

ClW <MRL 25.0 102 NA 101 103 (b)

CDW <MRL 25.0 104 96.8 98.9 92.1

O3W 2.3 25.0 87.3 NA 84.3 99.9 (b)

Bromate EDA RW <MRL 25.0 97.3 95.3 99.5 102

HIW <MRL 25.0 86.9 86.1 107 91.2

SW <MRL 25.0 100. 104 103 94.9

GW <MRL 25.0 83.2 101 88.4 88.3

ClW <MRL 25.0 105 NA 101 102 (b)

CDW <MRL 25.0 117 97.3 98.1 83.9

O3W 2.3 25.0 92.6 NA 84.5 88.9 (b)

NOTES:

(a) Degradation in the unpreserved matrix is apparent.

(b) NA indicates "NOT ANALYZED" 

(c) Analyte recovery will be adversely effected by reactions with free chlorine.
317.0 - 41

TABLE 3A. STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION 

 BY-PRODUCTS AND BROMIDE (cont.).1,2

Analyte Preservative Matrix

Unfortified

Conc.

(:g/L)

Fortified

Conc.

(:g/L)

Analyte % Recovery

Day

0

Day

3

Day

10

Day

30

See

Note

Bromide None RW <MRL 100 99.4 97.2 107 101

HIW <MRL 100 102 103 105 105

SW 31 100 102 97.1 107 99.1

GW 150 100 97.7 95.3 109 100.

ClW 4.7 100 8.90 NA(a) 37.0 11.4 (b,c,d)

CDW <MRL 100 5.78 23.1 39.0 51.3 (c,d)

O3W 30 100 98.3 NA 120 108 (b,d)

Bromide EDA RW <MRL 100 98.4 98.6 107 100.

HIW <MRL 100 104 103 106 105

SW 31 100 99.5 98.2 107 100.

GW 150 100 100. 97.0 114 97.7

ClW 12 100 101 NA 115 97.4 (b,c)

CDW 6.1 100 101 96.5 119 110 (c)

O3W 31 100 97.3 NA 122 102 (b)

Chlorate None RW <MRL 500 102 102 105 97.4

HIW <MRL 500 97.0 97.8 101 95.4

SW 5.8 500 100. 97.8 100. 96.0

GW <MRL 500 100. 98.7 101 99.8

ClW 38 500 102 NA 104 98.2 (b)

CDW 130 500 102 99.9 104 99.6

O3W 8.3 500 100. NA 103 97.3 (b)

Chlorate EDA RW <MRL 500 104 98.6 103 97.3

HIW <MRL 500 97.0 103 100. 95.0

SW 6.7 500 100. 98.2 100. 95.6

GW <MRL 500 102 97.0 101 99.3

ClW 38 500 101 NA 102 96.1 (b)

CDW 120 500 102 96.5 105 97.7

O3W 8.6 500 98.0 NA 103 96.4 (b)

NOTES:

(a) Degradation in the unpreserved matrix is apparent.

(b) NA indicates "NOT ANALYZED" 

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

(d) Measurement of Br-

 is not in the scope (source/raw water only) 
317.0 - 42

TABLE 4. INITIAL DEMONSTRATION OF CAPABILITY QC REQUIREMENTS.

Reference Requirement Specification and Frequency Acceptance Criteria

Sect. 9.2.2 

 9.3.1

 

Initial

Demonstration of

Low System

Background 

Analyze a method blank (LRB) and determine

that all target analytes are below 1⁄2 of the

proposed MRL prior to performing the IDC

The LRB

concentration must be

#1⁄2 of the proposed

MRL

Sect. 9.2.3 Initial

Demonstration of

Precision (IDP)

Conductivity: analyze 7 replicate LFBs

recommend fortify at 20 ug/L 

Absorbance: analyze 7 replicate LFBs

recommend fortify with bromate at 2.0 ug/L 

%RSD must be #20%

Sect. 9.2.4 Initial

Demonstration of

Accuracy (IDA)

Calculate average recovery of IDP replicates Mean % recovery

must be ± 15% of true

value.

Sect. 9.2.5 Quality Control

Sample (QCS)

Initially and at least quarterly analyze a QCS

from an external/second source

QCS must be ± 20%

of the true value

Sect. 9.2.6 Method

Detection Limit

(MDL)

Determination

Select a fortifying level at 3-5 times the

estimated instrument detection limit at or lower

than the MRL. Analyze 7 replicate LFBs

Calculate MDL using equation in Section 9.2.6

- do not subtract blank

Sect. 9.2.7 Minimum

Reporting Level

(MRL)

MRLs MUST be established for all analytes

during the IDC.

The low CAL

standard can be lower

than the MRL, but the

MRL MUST be no

lower than the low

CAL standard
317.0 - 43

TABLE 5. QUALITY CONTROL REQUIREMENTS (SUMMARY).

Reference Requirement Specification and Frequency Acceptance Criteria

Sect. 8.3 Sample Holding

Time /

Preservation

Bromate 28 days, refrig. at <6oC / 

 EDA Preservation

Bromide 28 days, EDA Permitted

Chlorate 28 days, refrig. at <6oC / EDA

Preservation

Chlorite 14 days, refrig. at <6oC / EDA

Preservation

Holding time and temperature

must not be exceeded. EDA

added to all samples

Sect.

11.1.4.1

(specific

to PCR)

Pretreated

Sample

(acidified/ Fe [II]

added to remove

chlorite) Holding

Time

ONLY REQUIRED when samples

containing chlorite are pretreated and PCR

is employed to measure trace bromate in

samples.

MAXIMUM PRETREATED SAMPLE

HOLDING TIME: 30 hours 

Pretreated sample holding time

must not be exceeded

Sect. 10.2 Initial

Calibration

Conductivity: generate calibration curve

using at least 5 standards

Absorbance: generate calibration curve

using at least 5 bromate standards

MRL MUST be no lower than

the lowest calibration standard

Sect.

10.3.1

Initial

Calibration

Check

Daily, verify calibration of conductivity

detector at the MRL by analyzing an initial

low-level continuing calibration check

standard (ICCS) and a separate low-level

ICCS for the absorbance detector at the

MRL.

Recovery must be 75- 125% of

the true value on both detectors

Sect.

10.3.2

 

Continuing

Calibration and

End Calibration

Checks

Alternately analyze separate mid and high

level CCCS/ECCS after every 10 samples

and after the last sample 

MRL to 5 x MRL must have 75 -

125% recovery on both

detectors

For 5 x MRL to highest CCCS 

must have 85 - 115% recovery

on both detectors

Sect. 9.3.1 Laboratory

Reagent Blank

(LRB)

Include LRB with every analysis batch (up

to 20 samples)

Analyze prior to analyzing field samples

All analytes must be 

# 1⁄2 MRL

Sect.

9.3.1.2

(specific

to PCR)

PRETREATED

Laboratory

Reagent Blank

(LRB)

REQUIRED in any analysis batch which

includes samples which have been

pretreated to remove chlorite prior to PCR

measurement of trace bromate.

PCR measured bromate 

< 1⁄2 MRL

Sect. 9.3.2 Laboratory

Fortified Blank

(LFB)

Laboratory must analyze LFB in each

analysis batch following the ICCS. 

Calculate %REC prior to analyzing

samples

LFB recovery if fortified at conc.

from MRL to 5X MRL must be

75 - 125%. For 5X MRL to

highest CCCS must be 85 -

115%. Must have acceptable

recoveries prior to analyzing

samples. Sample results from

batches that fail LFB are invalid
317.0 - 44

TABLE 5. QUALITY CONTROL REQUIREMENTS (SUMMARY CONTINUED).

Reference Requirement Specification and Frequency Acceptance Criteria

Sect. 9.3.3 Instrument

Performance

Check (IPC)

Calculate Peak Gaussian Factor (PGF)

using equation (Sect. 9.3.3.1) and

monitor retention time for surrogate in

Initial Calibration Check Standard

(ICCS) each day

PGF must fall between

0.80 and 1.15

Ret. Time (RT) for

surrogate must remain

80% of initial RT when

column was new

Sect. 9.4.1

Sect.

11.1.4.2

Laboratory

Fortified Sample

Matrix (LFM)

Must add known amount of each target

analyte to a minimum of 5% of field

samples or at least one within each

analysis batch for both detectors 

LFM must be fortified above the native

level and at no greater than 5 x the

highest field sample concentration 

Calculate target analyte recovery using

formula (Sect. 9.4.1.3)

When field samples from chlorine

dioxide plants which contain chlorite

are pretreated prior to the PCR

measurement of trace bromate, an

additional LFM must be prepared for

each pretreated field sample (Sect.

9.4.1.5) 

Recovery should be 

75 - 125%

If fortified sample fails the

recovery criteria, label

both as suspect/matrix.

Sect. 9.4.2 Surrogate Dichloroacetate is added to all blanks,

samples and standards (if measuring by

conductivity and absorbance)

Calculate recovery using formula in

Section 9.4.2

Surrogate recovery must

be 90 - 115%.

Samples that fail surrogate

recovery must be

reanalyzed. If second

analysis fails label result

as suspect/matrix 

Sect. 9.4.3 Field or

Laboratory

Duplicates

Analyze either a field or laboratory

duplicate for a minimum of 5% of field

samples or at least one within each

analysis batch for both detectors

Calculate the relative percent difference

(RPD) using formula in Section 9.4.3.1

The RPD for

concentrations at MRL to

5 x MRL should be ± 20%

on both detectors, and ±

10% on both detectors

for concentrations at 5 x

MRL to highest CCCS. If

this range is exceeded, 

label both as

suspect/matrix 
317.0 - 45

TABLE 6. EXAMPLE SAMPLE ANALYSIS BATCH WITH QUALITY CONTROL

REQUIREMENTS

Injection 

#

Sample

 Description

Acceptance 

Criteria 

1 Laboratory reagent blank (LRB) # 1⁄2 MRL

2 ICCS conductivity detector (5.0 μg/L) 3.75 to 6.25 μg/L

3 ICCS absorbance detector (0.5 μg/L) 0.375 to 0.625 μg/L

4 Laboratory Fortified Blank (LFB) - 

conductivity detector

 ± 25 % fortified level

5 LFB - absorbance detector ± 25 % fortified level

6 Field sample 1

7 Field sample 1 - Laboratory Duplicate (LD) (a) ± 15 % RPD

8 Field sample 2

9 Field sample 2 - Laboratory Fortified Matrix (LFM) (a) at

concentrations specific for conductivity detector 

 ± 25% fortified level

10 Field sample 2 - LFM specific for trace bromate on the

absorbance detector

 ± 25% fortified level

11 Field sample 3

12 Field sample 4

13 Field sample 5

14 Field sample 6

15 Field sample 7

16 Field sample 8

17 Field sample 9

18 Field sample 10

19 CCCS conductivity detector (75.0 μg/L) 63.8 to 86.3 μg/L

20 CCCS absorbance detector (5.0 μg/L) 4.25 to 5.75 μg/L

21 Field sample 11

22 Field sample 12
317.0 - 46

23 Field sample 13

24 Field sample 14 - (finished water from PWS using chlorine

dioxide)

25 Pretreated LRB (Section 9.3.1.2) using the acid/Fe(II)

chlorite removal procedure (Section 11.1.4)

# 1⁄2 MRL

26 Field sample 14 (b) - (finished water from PWS using

chlorine dioxide) pretreated with acid/Fe(II) (Section

11.1.4)

27 Field sample 14 - (finished water from PWS using chlorine

dioxide) LFM specific for trace bromate on the absorbance

detector, pretreated with acid/Fe(II) (Section 11.1.4.2) 

 ± 25% fortified level

28 Field sample 15

29 Field sample 16

30 Field sample 17

31 Field sample 18

32 Field sample 19(b)

33 ECCS conductivity detector (500.0 μg/L) 425 to 575 μg/L

34 ECCS absorbance detector (15.0 μg/L) 12.8 to 17.3 μg/L

(a) If no analytes are observed above the MRL for a sample, an alternate sample which contains reportable

values should be selected as the laboratory duplicate. Alternately, the LFM can be selected and

reanalyzed as the laboratory duplicate ensuring the collection of QC data for precision.

(b) Field sample #19 was the final field sample permitted in this batch but 20 total field samples were

analyzed. 

Field sample #14 was analyzed both initially and as a acid/Fe (II) pretreated sample, therefore, it

accounted for two “field sample analyses” toward the maximum of twenty in an analysis batch (Section

3.1).
317.0 - 47

Figure 1: Schematic detailing the configuration of postcolumn hardware addition to an ion

chromatograph. Mention of trade names or commercial products does not constitute

endorsement or recommendation for use. If the requirements found in Section 9 are met,

equivalent products or hardware can be employed.

NOTE: In a typical Method 300.1 hardware configuration, a backpressure coil is included after

the conductivity cell as part of the waste stream when this manufacturer’s equipment is used. 

These backpressure coils are not required when the Method 317.0 instrument configuration is

employed since the additional PCR system components, placed in-line, function in the same

capacity and provide sufficient backpressure.
317.0 - 48

Figure 2: Reagent water fortified with inorganic disinfection by-products and bromide at 10

ug/L. 
317.0 - 49

Figure 3: Chlorinated tap water fortified with bromate at 2.0 ug/L.