321.8-1

METHOD 321.8

DETERMINATION OF BROMATE IN DRINKING WATERS

BY ION CHROMATOGRAPHY

INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY

Revision 1.0

EMMC Version

John T. Creed, Carol A. Brockhoff and Theodore D. Martin

Revision 1.0 December 1997.
321.8-2 

NATIONAL EXPOSURE RESEARCH LABORATORY

OFFICE OF RESEARCH AND DEVELOPMENT

U.S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OHIO 45268

METHOD 321.8

DETERMINATION OF BROMATE IN DRINKING WATERS 

BY ION CHROMATOGRAPHY

INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY

1.0 SCOPE AND APPLICATION

1.1 This method provides a procedure for determination of bromate in drinking water.

 Chemical Abstract Services

Analyte Registry Numbers (CASRN)

__________________________________________________________

Bromate (BrO3

-

) 15541-45-4

1.2 For reference where this method is approved for use in compliance monitoring programs

[e.g., Safe Drinking Water Act (SDWA)], consult both the appropriate sections of the

Code of Federal Regulation (Part 141 § 141.23 for drinking water), and the latest

Federal Register announcements. 

1.3 This method should be used by analysts experienced in the use of inductively coupled

plasma mass spectrometry (ICP-MS), and the interpretation of spectral and matrix

interferences. A minimum of six months experience with commercial instrumentation is

recommended. It is also recommended that the analyst have experience in liquid

chromatography and the use of ICP-MS as a chromatographic detector. 

1.4 Users of the method data should state the data-quality objectives prior to analysis. Users

of the method must document and have on file the required Initial Demonstration of

Performance data described in Section 9.2 prior to using the method for analysis. 

2.0 SUMMARY OF METHOD

2.1 An aliquot of a finished drinking water is passed through a preparatory cartridge capable

of removing the trisubstituted haloacetic acids which interfere with the analysis of

bromate. The sample is then injected onto a column which separates the remaining

brominated haloacetic acids and bromide from the bromate. The ICP-MS is interfaced

to the ion chromatograph and both mass 79 and mass 81 are monitored in time as
321.8-3 

bromate elutes from the column. The resulting signal is integrated and a concentration

determined from a calibration curve. Mass 79 is used for quantitation while mass 81

provides isotope ratio information which can be used to screen for potential polyatomic

interferences. 

2.2 Chromatography: The chromatographic separation is based on an anion exchange resin.

The sample is injected on the column and the matrix and analyte partition themselves

between the mobile phase and the stationary phase as they move along the column.

Early eluting analytes spend most of their time in the mobile phase while the late eluting

compounds spend a larger percentage of their time interacting with the stationary phase.

The matrix anions can influence retention times by blocking the interaction of the

stationary phase with the analytes producing a shift in the retention time.

Inductively Coupled Plasma Mass Spectrometer: The detection technique is based on

the use of an ICP-MS for the detection of trace elements[1-3]. The chromatographic

eluent is introduced by pneumatic nebulization into a radio frequency plasma where

energy transfer processes cause desolvation, atomization and ionization. The ions are

extracted from the plasma through a differentially pumped vacuum interface and

separated on the basis of their mass-to-charge ratio by the mass spectrometer having a

minimum resolution capability of 1 amu peak width at 5% peak height. The ions

transmitted through the mass spectrometer are detected by an electron multiplier or

Faraday detector and the ion information is processed by the data system. Interferences

relating to the technique (Sect. 4) must be recognized.

Although ICP-MS is typically used for multi-analyte determinations, it is used in 321.8

for species specific quantification. In this mode the signal response is recorded via

chromatographic or time resolved software. The use of ion chromatography in

combination with ICP-MS detection has been reported for the detection of bromate [4-

7].

DEFINITIONS

3.1 Calibration Blank - A volume of reagent water pH adjusted (to 10) with the same base

as in the calibration standards.

3.2 Calibration Standard (CAL) - A solution prepared from the dilution of stock standard

solutions. The CAL solutions are used to calibrate the instrument response with respect

to analyte concentration. This solution is pH adjusted to 10.

3.3 Instrument Performance Check (IPC) Solution - A solution of method analytes, used

to evaluate the performance of the instrumental system with respect to defined set of

method criteria. Within this method, the IPC is identical to the laboratory fortified

blank. 
321.8-4 

3.4 Drift Standard- A calibration standard added to a post column sample loop (via a

second valve) which is transported into the plasma when the sample is injected. This

analyte does not traverse the column and is used to compensate for instrumental (ICPMS) drift during the analysis of a set of samples.

3.5 Laboratory Duplicates (LD1 and LD2) - Two aliquots of the same sample taken in

the laboratory and analyzed separately with identical procedures. Analyses of a number

of LD1 and LD2 indicates precision associated with laboratory procedures, but not with

sample collection, preservation, or storage procedures.

3.6 Laboratory Fortified Blank (LFB) - An aliquot of LRB to which known quantities of

the method analyte is added in the laboratory. The LFB is analyzed exactly like a

sample, and its purpose is to determine whether the methodology is in control and

whether the laboratory is capable of making accurate and precise measurements. 

3.7 Laboratory Fortified Sample Matrix (LFM) - An aliquot of an environmental sample

to which known quantities of the method analyte is added in the laboratory. The LFM

is analyzed exactly like a sample, and its purpose is to determine whether the sample

matrix contributes bias to the analytical results. The background concentrations of the

analytes in the sample matrix must be determined in a separate aliquot and the measured

values in the LFM corrected for background concentrations.

3.8 Laboratory Reagent Blank (LRB) - An aliquot of reagent water or other blank

matrices that are treated exactly as a sample including exposure to all glassware,

equipment, solvents, and reagents that are used with other samples. The LRB is used

to determine if method analyte or other interferences are present in the laboratory

environment, reagents, or apparatus.

3.9 Linear Dynamic Range (LDR) - The concentration range over which the instrument

response to an analyte is linear.

3.10 Method Detection Limit (MDL) - The minimum concentration of an analyte that can

be identified, measured, and reported with 99% confidence that the analyte

concentration is greater than zero.

3.11 Quality Control Sample (QCS) - A solution of the method analyte of known

concentrations which is used to fortify an aliquot of LRB or sample matrix. The QCS

is obtained from a source external to the laboratory and different from the source of

calibration standards. It is used to check either laboratory or instrument performance.

3.12 Stock Standard Solution - A concentrated solution containing the method analytes

prepared in the laboratory using assayed reference materials or purchased from a

reputable commercial source.

3.13 Tuning Solution - A solution which is used to determine acceptable instrument
321.8-5 

performance prior to calibration and sample analyses.

3.14 Water Sample - For the purpose of this method, a sample taken from a finished

drinking water supply. 

4.0 INTERFERENCES

4.1 Several interference sources may cause inaccuracies or imprecisions in the

determination of bromate by ICP-MS. These are:

4.1.2 Abundance sensitivity - This is a property defining the degree to which the

”wings” of a mass peak contribute to adjacent masses. The abundance

sensitivity is affected by ion energy and operating pressure. “Wing” overlap

interferences may result when a small ion peak is being measured adjacent to

a large one. The potential for these interferences should be recognized and the

mass spectrometer operating conditions adjusted to minimize the effect.

 

This interference is relevant in this method given the large 40Ar40Ar+ dimer

adjacent to mass 79 which is present in conventional ICP-MS. The extent to

which the dimer contributes to the signal on mass 79 can be determined by

scanning over masses 76-83 using 20 points per amu (skipping mass 80) using

a 5mM HNO3 solution(See Figure 1). The interference signal from the argon

dimer is apparent by examining the background signal at mass 79.4 relative to

76.4, 77.4 and 78.4. With proper mass calibration and adequate abundance

sensitivity, the signal on masses 76.4, 77.4, and 78.4 should be close to normal

photon background. The signal on 79.4 commonly is elevated relative to the

above masses. This elevated signal is caused by the mass spectrometers

insufficient abundance sensitivity.

The signal should decrease as the mass decreases from 79.5 to 79.3 etc. To

determine if the instrument has adequate abundance sensitivity the decrease

(79.5 to 79.3) in this signal should be extrapolated to mass 79.0 at which point

it should be no higher than twice the normal photon background(See Figure 1).

The signal may increase as mass 79.0 is approached depending on the bromide

contamination in the 5mM HNO3. The resolution etc., should be adjusted to

minimize the dimers contribution to mass 79.0.

Note: If the decrease in the signal from 79.5 to 79.0 does not have

an inflection point, this may indicate that the abundance sensitivity is

insufficient to resolve 79Br+ from 40Ar40Ar+ 

4.1.3 Isobaric polyatomic ion interferences are caused by ions consisting of more

than one atom which have the same nominal mass-to-charge ratio as the isotope

of interest, and which cannot be resolved by the mass spectrometer in use[8].

These ions are commonly formed in the plasma or interface system from
321.8-6 

support gases or sample components. The two polyatomics which are inherent

to conventional ICP-MS are the 40Ar38ArH and 40Ar40ArH. 40Ar40ArH

contributes to the background signal on mass 81. To minimize this, it is

recommended that the sample flow rate remain on between injections. This will

produce smoother baselines on mass 81 and thereby produce more reproducible

integrations on mass 81 for the early eluting peaks.

The ICP-MS interferences which apply to the detection of bromate are listed

in Table 1. These spectral interferences are common to the plasma or

produced by matrix anions eluting from the column. These interferences are

outside the retention window for bromate but may cause baseline shifts which

will degrade integration precision.

4.1.4 Physical interferences are associated with the physical processes which govern

the transport of sample into the plasma, sample conversion processes in the

plasma, and the transmission of ions through the plasma-mass spectrometer

interface. These interferences may result in differences between instrument

responses for the sample and the calibration standards. Samples containing high

concentration of chloride (which elutes immediately after bromate) may cause

chromatographic baseline shift possibly from a small change in the 40Ar40ArH

production during the chloride elution. In addition, the removal of high

concentrations of sodium and potassium which may exist in the drinking water

are removed by using an anion self regenerating suppressor. This minimizes

their deposition on the sampling cone and thus improves long term stability.

Note: The mobile phase in this method was chosen based on its

ability to produce a stable baseline and sensitivity over a multiple

week period. The long term stability of the instrument is monitored

by injecting a post column drift standard with each chromatogram.

The analyte concentration in a sample is corrected by using this drift

standard in the same fashion that an internal standard is used in

Method 200.8[9].

4.1.5 Baseline Drift - This results when a constituent from the sample matrix is not

quantitatively removed from the column leading to a slow column bleed of the

strongly retained species. If this is suspected, the column should be flushed

according to the manufacturer’s recommendations. A slowly rising baseline

can be caused by trisubstituted brominated haloacetic acids.

4.1.6 Chromatographic Interferences - The known chromatographic interferences for

the determination of bromate in drinking water via ICP-MS detection are listed

in Table 1 and their approximate retention characteristics are reported in Figure

2. These known interferences have been chromatographically resolved using

the procedure described in this method. Given the diversity of environmental

samples, the possibility of unidentified interferences exist. The following
321.8-7 

section is written to provide the analyst with some guidance if an interference

is identified. The two possible interferences are chromatographic overlap with

a bromine containing species or a co-eluting polyatomic. In the case of coelution with a bromine containing anion it is recommended that the analyst try

the following method modifications in the order presented in an attempt to

resolve the co-elution. 

1.) Use weaker mobile phases (i.e. lower NH4NO3

concentrations).

2.) Alternative columns.

3.) Pretreatment cartridge which selectively removes the

interference.

This co-elution should be documented and the changes in the mobile and

stationary phase should produce a method capable of meeting all requirements

in Section 9.

In the case of a co-elution with a polyatomic interference (on mass 79), the

recommendation to the analyst is to try the following method modifications in

the order presented in an attempt to resolve the co-elution.

1.) Use mass 81 for quantitation.

2.) Use weaker mobile phases.

3.) Alternative columns

4.) Pretreatment cartridge to selectively remove the interference.

This co-elution should be documented and the changes in the mobile and

stationary phase should produce a method capable of meeting all requirements

in Section 9.

4.1.7 Samples that contain particles larger than 0.45 microns and reagent solutions

that contain particles larger than 0.2 micron require filtration to prevent damage

to instrument columns and HPLC pumping system.

4.1.8 The analyst should be aware of the potential for carryover peaks from one

analysis which will effect the proper detection of bromate in the subsequent

analysis. Carryover was not observed in the analysis listed in Table 3 using the

column, mobile phase and flow rate reported in Table 2. However, the analyst

should be aware of the potential for carryover peaks.

4.1.9 Retention time shifts in ion chromatography are possible do to weak eluent

strengths and high ionic strength matrices. These shifts are minimized by the

eluent system reported in table 2. However, the analyst should be aware of the

potential for retention time shifts do to high ionic strength matrices. These

effects can be minimized by dilution of the sample matrix. 
321.8-8 

5.0 SAFETY

5.1 The toxicity or carcinogenicity of bromate and reagents used in this method have not

been fully established. Each chemical should be regarded as a potential health hazard

and exposure to these compounds should be as low as reasonably achievable. Each

laboratory is responsible for maintaining a current awareness file of OSHA regulations

regarding the safe handling of the chemicals specified in this method [10,11]. A reference

file of material data handling sheets should also be available to all personnel involved in

the chemical analysis. Specifically, concentrated nitric presents various hazards as it is

moderately toxic and extremely irritating to skin and mucous membranes. Use these

reagents in a fume hood whenever possible and if eye or skin contact occurs, flush with

large volumes of water. Always wear safety glasses or a shield for eye protection,

protective clothing, and observe proper mixing when working with these reagents.

5.2 Analytical plasma sources emit radio frequency radiation, in addition to intense UV

radiation. Suitable precautions should be taken to protect personnel from such hazards.

The inductively coupled plasma should only be viewed with proper eye protection from

UV emissions.

5.3 It is the responsibility of the user of this method to comply with relevant disposal and

waste regulations. For guidance see Sections 14.0 and 15.0. 

6.0 EQUIPMENT AND SUPPLIES

6.1 Inductively coupled plasma mass spectrometer. This instrument must meet the following

requirements:

6.1.1 An instrument capable of scanning the mass range 5-250 amu with a minimum

resolution capability of 0.75 amu peak width at 5% peak height is required.

This instrument may be fitted with a conventional or extended dynamic range

detection system. The abundance sensitivity must be greater than 1.0 x 106 on

the low side of mass 80 or such that the dimer’s (40Ar40Ar+)low mass shoulder

does not influence mass 79. 

6.1.2 Radio-frequency generator compliant with FCC regulations.

6.1.3 Argon gas supply - High purity grade (99.99%). When analyses are conducted

frequently, liquid argon is more economical.

6.1.4 A variable-speed peristaltic pump may be used to pump the drain of the spray

chamber to waste.

6.1.5 A mass-flow controller on the nebulizer gas supply is required. A water-cooled

spray chamber may be of benefit in reducing the water vapor entering the
321.8-9 

plasma and thereby minimizing the 40Ar40ArH+. A double-pass spray chamber

is recommended to increase background stability on mass 81 if 40Ar40ArH+ is

present in the spectrum generated while nebulizing the mobile phase.

6.1.6 If an electron multiplier detector is being used, precautions should be taken,

where necessary, to prevent exposure to high ion flux. Otherwise, changes in

instrument response or damage to the multiplier may result. This may be true

for samples containing bromide in the parts per million range.

6.1.7 A nebulizer with a low dead volume is recommended. 

6.2 Ion Chromatograph. This instrument must meet the following specifications: 

6.2.1 Eluent Pump - Programmable flow high pressure pumping system capable of

delivering pressures up to 3000 psi and flow rates up to 1.5 ml/min.

6.2.2 Control Valves - Inert double stacked pneumatic operated 4 way valves capable

of withstanding 3000 psi.

6.2.3 Sample Loops- narrow bore, high pressure tefzel® tubing or equivalent.

6.2.4 Tubing- narrow bore high pressure tefzel® tubing or equivalent.

6.2.5 Guard and Analytical Column - Dionex PA-100 or equivalent.

6.2.6 Suppressor - Dionex (ASRS) anion self regenerating suppressor or equivalent.

6.2.7 Pretreatment Cartridges - Dionex On-Guard-RP or equivalent 

6.3 Analytical balance, with capability to measure to 0.1 mg, for use in weighing samples

and preparing standards.

6.4 An air displacement pipette capable of delivering volumes ranging from 50 to 2500 μL

with an assortment of high quality disposable pipet tips. Calibration of the pipette

should be verified frequently by weighing aliquots of distilled deionized water using the

analytical balance to assure precision and accuracy of the pipette. 

6.5 Labware - For determination of bromate, plastic labware has been used exclusively and

measurable concentrations of bromate in the blank have not been observed. 

6.5.1 Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with

ETFE (ethylene tetrafluorethylene) screw closure, 125-mL to 250-mL

capacities.

6.5.2 One-piece stem FEP wash bottle with screw closure, 125-mL capacity.
321.8-10 

6.5.3 Syringes- 10cc Becton-Dickinson plastic syringes or equivalent.

7.0 REAGENTS AND STANDARDS

7.1 Reagents may contain elemental impurities that might affect the integrity of analytical

data. Due to the high sensitivity of ICP-MS, high-purity reagents should be used

whenever possible. All acids used for this method must be of ultra high-purity grade.

The acid used to prepare the 5mM HNO3 in the mobile phase does contain some

bromide background. Care should be taken to minimize this background intensity.

7.1.1 Nitric acid, concentrated (sp.gr. 1.41).

7.1.2 Nitric acid (1+1) - Add 500 mL conc. nitric acid to 400 mL of reagent grade

water and dilute to 1L.

7.1.3 Ammonium Nitrate - Fisher ACS certified or equivalent.

7.1.4 Sodium Hydroxide - Fisher 50/50 liquid mixture or equivalent.

7.2 Reagent water - All references to reagent grade water in this method refer to ASTM

type I water (ASTM D1193)[12]. Suitable water may be prepared by passing distilled

water through a mixed bed of anion and cation exchange resins.

7.3 Standard Stock Solutions - Stock standards may be purchased from a reputable

commercial source or prepared from ultra high-purity grade chemicals. These standards

have extremely low ionic strengths and should be pH adjusted to 10 (with NaOH)in

order to minimize bromate interaction with the plastic sample loop tubing[6]. Replace

stock standards when they can not be verified with QC standards. 

7.3.1 Preparation of calibration standards - a fresh bromate standard should be

prepared once a month or as needed. Dilute the stock bromate standard solution to levels appropriate to the operating range of the instrument using reagent

water and adjust the pH to 10 using NaOH. The bromate concentrations in the

standards should be sufficiently high to produce good isotope ratio precision

(<2%) and to accurately define the slope of the response curve. Depending on

the sensitivity of the instrument, concentrations ranging from 10 μg/L to 50

μg/L are suggested.

Note: A blank and one calibration standard or multi-point

calibration can be utilized to calibrate the response of the instrument.

7.4 Drift standard - The drift standard should be made such that its concentration is

approximately five times higher than the bromate calibration standard. (This will

compensate for the sample loop volume difference between the sample and the drift

standard.) The drift standard concentration should be chosen based on analytical
321.8-11 

precision (< 5% rsd of replicate peak integration).

7.5 Blanks - The calibration blank is used to establish and verify the analytical calibration.

7.5.1 Calibration blank - Consists of reagent grade water which is pH adjusted to 10

with sodium hydroxide.

7.6 Tuning Solution - This solution is used for instrument tuning (lens, argon flows etc.),

mass calibration and abundance sensitivity prior to analysis. The tuning solution should

be approximately twice the bromate calibration standard concentration (producing

greater than 30,000cps) and should be delivered to the plasma using a peristaltic pump

at a flow rate of 1 mL/min. The instrument should be tuned for maximum signal-tonoise using mass 79. After tuning, the tuning solution should be analyzed by scanning

over masses 76-84 using 20 points per amu (skipping mass 80). This data can be used

to verify the mass calibration (mass shifts of greater than 0.1 amu should be corrected)

and check the instrument sensitivity (approximately 35,000cps/100ppb bromate given

the instrument conditions outlined in Table 2). The calibration blank or a 5mM HNO3

solution should then be analyzed using the same scanning conditions to check the mass

analyzer’s abundance sensitivity. This preanalysis routine should be performed daily(see

figure 1).

 

7.7 Quality Control Sample (QCS) - The QCS should be obtained from a source outside the

laboratory. The concentration of the QCS solution analyzed will depend on the

sensitivity of the instrument. To prepare the QCS dilute an appropriate aliquot bromate

to a concentration which is approximately 75% of the concentration of the highest

calibration standard. The QCS should be analyzed as needed to meet data-quality needs

and a fresh solution should be prepared quarterly or more frequently as needed. 

7.8 Laboratory Fortified Blank (LFB) - To an aliquot of Calibration Blank add an aliquot

of the stock standard solution to prepare the LFB. The fortified concentration should

produce percent relative standard deviations of 4-7% on replicate determinations. The

LFB must be carried through the same entire preparation scheme as the samples. This

solution should be pH adjusted to 10 with sodium hydroxide.

8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 The pH of all aqueous samples should be tested immediately prior to analysis to ensure

the sample has been properly preserved. If the sample requires a pH adjustment

throughly mix the sample after the sodium hydroxide has been added. The pH of the

sample must be adjusted to 10. This pH adjustment should be performed just prior to

analysis. This pH adjustment assures the solubility of bromate within the sample

loop[6].
321.8-12 

loop[6]. 

8.2 If required by the data user, prepare a field blank using reagent water. Use the same

sample containers (see section 6.5.1 for container recommendations)as used in sample

collection.

 

9.0 QUALITY CONTROL

9.1 Each laboratory using this method is required to operate a formal quality control (QC)

program. The minimum requirements of this program consist of an initial demonstration

of laboratory capability, and the periodic analysis of laboratory calibration blanks,

fortified blanks and calibration solutions as a continuing check on performance. The

laboratory is required to maintain performance records that define the quality of the data

generated.

NOTE: Because the sample preparation step of this method is limited to pH

adjustment prior to analysis, the number of required solutions needed to verify

data quality has been reduced. In this method the calibration blank (Section 7.5

and 9.3) is used to establish baseline calibration and is used to verify the

absence of contamination. The laboratory fortified blank (Sections 7.8 and 9.3)

is used to assess both method accuracy and instrument performance.

9.2 Initial Demonstration of Performance (mandatory)

9.2.1 The initial demonstration of performance is used to characterize instrument

performance (determination of linear calibration range and analysis of quality

control sample) and laboratory performance (determination of method

detection limit) prior to analyses conducted by this method.

9.2.2 Linear dynamic range - Linear dynamic range is detector or chromatographic

resolution limited.

The useable linear range must be determined for the instrument configuration

to be used.

Note: The linear dynamic range may be limited by the chromatographic

resolution of bromate from bromoacetic acid or other interferences. In this

situation, the linear calibration range is limited to a concentration of

bromate which can be chromatographically resolved from bromoacetic acid.

Given the experimental conditions in Table 2, the linear dynamic range was

limited to 50μg/L based on chromatographic resolution.

9.2.3 Quality control sample (QCS) - When beginning the use of this method, on a

quarterly basis or as required to meet data-quality needs, verify the calibration
321.8-13 

standards and acceptable instrument performance with the preparation and

analyses of a QCS. To verify the calibration standards, the determined mean

concentration from three analyses of the QCS must be within ± 10% of the

stated QCS value. If the calibration standards cannot be verified, the source of

the problem must be identified and corrected before either proceeding on with

the initial determination of method detection limits or continuing with on-going

analyses.

9.2.4 Method detection limit (MDL)- This should be established using reagent water

(blank) fortified at a concentration of two to five times the estimated detection

limit[13]. To determine MDL values, take seven replicate aliquots of the

fortified reagent water and process through the entire analytical method.

Perform all calculations defined in the method and report the concentration

values in the appropriate units. Calculate the MDL as follows:

 MDL = (t)(n-1,1-alpha = 0.99) x (S)

where:

(t)(n-1,1-alpha = 0.99) = 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].

n = number of replicates

S = standard deviation of the replicate analyses.

The MDL should be determined annually, when a new operator begins work

or whenever, in the judgement of the analyst, a change in analytical

performance caused by either a change in instrument hardware or operating

conditions would dictate they be redetermined.

The MDL for bromate using the conditions listed in Table 2 is 0.3 Fg/L. 

 

9.3 Assessing Laboratory Performance (mandatory)

 

9.3.1 Calibration blank - Within this method a calibration blank and the

laboratory reagent blank are operationally the same. The calibration blank

will be used as the LRB and a fresh calibration blank should be made daily to

verify the lack of contamination. 

Analysis of the calibration blank can be used to verify the calibration baseline

and to assess chromatographic carryover interference or contamination. The

calibration blank should be analyzed as a sample. If the calibration blank

produces an integrable signal for bromate, the laboratory should find the source

of this problem prior to analyzing samples. The laboratory must complete the

analysis of one calibration blank with each batch of 20 samples.
321.8-14 

9.3.2 Laboratory fortified blank (LFB) - Within this method the LFB is used to

assess both laboratory and instrument performance. The laboratory must

analyze at least one LFB (Sect. 7.8) immediately after calibration and after each

10 samples. Calculate accuracy as percent recovery using the following

equation:

 LFB - CB 

R = ))))))))) x 100

s 

where: R = percent recovery.

LFB = laboratory fortified blank concentration.

CB = calibration blank concentration.

S = concentration equivalent of analyte added

to fortify the CB solution.

If the recovery falls outside the required control limits of 85-115%, bromate is

judged out of control, and the source of the problem should be identified and

resolved before continuing analyses.

9.3.3 The laboratory must use LFB analyses data to assess laboratory performance

against the required control limits of 85-115%. When sufficient internal

performance data become available (usually a minimum of twenty to thirty

analyses), optional control limits can be developed from the mean percent

recovery (x) and the standard deviation (S) of the mean percent recovery.

These data can be used to establish the upper and lower control limits as

follows:

 UPPER CONTROL LIMIT = x + 3S

 LOWER CONTROL LIMIT = x - 3S

The optional control limits must be equal to or better than the required control

limits of 85-115%. After each five to ten new recovery measurements, new

control limits can be calculated using only the most recent twenty to thirty data

points. Also, the standard deviation (S) data should be used to establish an ongoing precision statement for the level of concentrations included in the LFB.

These data must be kept on file and be available for review.

Note: Using the experimental conditions in Table 2, the average recovery

of the LFB was 99.8% with a three sigma control limit of 10.2%

9.3.4 Instrument performance - For all determinations the laboratory must check

instrument performance and verify that the instrument is properly calibrated on

a continuing basis. This is accomplished via the recovery on the LFB (85-

115%,section 9.3.2) and monitoring the instrument drift standard injected with
321.8-15 

115%,section 9.3.2) and monitoring the instrument drift standard injected with

each sample.

9.3.5 Instrument Drift Standard - The analyst is expected to monitor the response

from the instrument drift standard(in each sample) throughout the sample set

being analyzed. The absolute response of any one drift standard must not

deviate more than 70-130% of the original response associated with the

calibration blank. If deviations greater than these are observed, the reason for

the drift should be investigated. Possible causes of drift may be a partially

blocked sampling cone or a change in the tuning condition of the instrument.

9.4 Assessing Analyte Recovery and Data Quality 

9.4.1 The chemical nature of the sample matrix can affect analyte recovery and the

quality of the data. Taking separate aliquots from the sample for replicate and

fortified analyses can in some cases assess the effect. Unless otherwise

specified by the data user, laboratory or program, the following laboratory

fortified matrix (LFM) procedure is required. 

9.4.2 The laboratory must add a known amount of analyte to a minimum of 10% of

the routine samples. In each case the LFM aliquot must be a duplicate of the

aliquot used for sample analysis. The added bromate concentration must be the

same as that used in the laboratory fortified blank. Over time all routine sample

sources should be fortified.

9.4.3 Calculate the percent recovery for bromate, corrected for background

concentrations measured in the unfortified sample, and compare these values

to the designated LFM recovery range of 70-130%. Percent recovery may be

calculated using the following equation:

 Cs - C

R = )))))) x 100

 s

where: R = percent recovery.

Cs = fortified sample concentration.

C = sample background concentration.

 s = concentration equivalent of bromate added to fortify the

sample.

Note: The precision and recovery in six drinking water matrices are

reported in Table 3.

9.4.4 If recovery falls outside the designated range and laboratory performance is
321.8-16 

shown to be in control, the recovery problem encountered with the fortified sample is

judged to be matrix related, not system related. The data user should be informed that

the result for the unfortified sample is suspect due to an uncorrected matrix effect. 

10.0 CALIBRATION AND STANDARDIZATION

10.1 Operating conditions - Because of the diversity of instrument hardware, no detailed

instrument operating conditions are provided. The analyst is advised to follow the

recommended operating conditions provided by the manufacturer. It is the responsibility

of the analyst to verify that the instrument configuration and operating conditions satisfy

the analytical requirements of this method and to maintain quality control data verifying

instrument performance and analytical results. Instrument operating conditions which

were used to generate precision and recovery data for this method are included in Table

2.

10.2 Precalibration routine - The following precalibration routine must be completed prior to

calibrating the instrument.

10.2.1 Initiate proper operating configuration of instrument and data system. Allow

a period of not less than 30 min for the instrument to warm up. Conduct mass

calibration and resolution checks using the tuning solution. The tuning solution

should be analyzed by scanning over masses 76-83 using 20 points per amu

(skipping mass 80). For good performance, adjust spectrometer resolution to

produce a peak width of approximately 0.75 amu at 5% peak height. Adjust

mass calibration if it has shifted by more than 0.1 amu from unit mass. The

abundance sensitivity must be checked by analyzing the calibration blank(See

Figure 1). 

10.3 Instrument drift - An instrument drift solution must be injected into the column effluent

at the same time a sample is injected onto the column to verify instrument drift

throughout the analysis of a set of samples. This solution does not traverse the column.

The correction factor is calculated by ratioing the drift standard response in the

calibration solution to the drift standard response in the current sample. This correction

factor is then multiplied by the sample concentration. This is similar to an internal

standard correction used in EPA Method 200.8[9].

Note: The stability of the baseline on mass 81 is strongly influenced by the IC

pump being turned on and off. Therefore it is recommended that this pump

remain on throughout an analysis set. 

10.4 Calibration - Prior to initial calibration, set up proper instrument software routines for

the collection of time resolved data. (See Table 2 for the experimental parameters used

to collect the data within the method.) The instrument must be calibrated using the

calibration blank and a calibration standard prepared at one or more concentration levels.
321.8-17 

calibration blank and a calibration standard prepared at one or more concentration levels.

If single point calibration is used, the standard concentration should be near the

determined upper linear range. 

10.5 The rinse blank should be used to flush the IC injection loop and by-pass loops. This

procedure is recommended between injections.

11.0 PROCEDURE

11.1 Aqueous Sample Preparation - The sample must be adjusted to pH 10 prior to analysis.

The sample must be room temperature and pretreated with an on-guard RP cartridge

prior to analysis. The RP cartridges were used according to the manufacturer’s

recommendations. Trisubstituted haloacetic acids (removed by the RP cartridge) can

cause a slowly rising baseline because these trisubstituted haloacetic acids are strongly

retained on the column.

11.2 The sample is injected onto the column at the same time the instrument drift standard is

injected into the post column mobile phase. For sample and drift standard sample loop

volumes see table 2. 

11.3 Samples having concentrations higher than the established linear dynamic range should

be diluted into range and reanalyzed.

12.0 DATA ANALYSIS AND CALCULATIONS

12.1 Sample data should be reported in units of μg/L for aqueous samples. Do not report

bromate concentrations below the determined MDL. Drift standard correction should

be applied to all sample concentrations.

12.2 For data values less than ten, two significant figures should be used for reporting

element concentrations. For data values greater than or equal to ten, three significant

figures should be used.

12.3 If additional dilutions were made to any samples, the appropriate dilution factor should

be applied.

12.4 The primary quantitative isotope should be 79 because it has the most stable background

and is less prone to the known interferences. Mass 81 should be monitored to verify

that the bromide isotope ratio within the retention window is near unity. A ratio of the

two isotopes can provide useful information for the analyst in detecting a possible

spectral interference. 

12.5 The QC data obtained during the analyses provide an indication of the quality of the

sample data and should be provided with the sample results.
321.8-18 

13.0 METHOD PERFORMANCE

13.1 Instrument operating conditions used for single laboratory testing of the method are

summarized in Table 2. 

13.2 Data obtained from single laboratory testing of the method are summarized in Table 3

for six drinking water samples. The average concentrations reported in the second

column are the native bromate concentrations. The percent relative standard deviations

associated with the native concentrations are reported in the second column. The

samples were then fortified with 25Fg/L bromate. The average recovery and precision

of this recovery is reported in the 4th and 5th columns respectively.

14.0 POLLUTION PREVENTION

14.1 Pollution prevention encompasses any technique that reduces or eliminates the quantity

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

prevention exist in laboratory operation. The EPA has established a preferred hierarchy

of environmental management techniques that places pollution prevention as the

management option of first choice. Whenever feasible, laboratory personnel should use

pollution prevention techniques to address their waste generation. When wastes cannot

be feasibly reduced at the source, the Agency recommends recycling as the next best

option.

14.2 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 Relations and Science Policy, 1155 16th Street N.W., Washington D.C.

20036, (202)872-4477.

15.0 WASTE MANAGEMENT

15.1 The Environmental Protection Agency requires that laboratory waste management

practices be conducted consistent with all applicable rules and regulations. 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

sewer discharge permits 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 the Section 14.2.
321.8-19 

16. References

1. Gray A.L. and A. R. Date. Inductively Coupled Plasma Source Mass Spectrometry

Using Continuum Flow Ion Extraction. Analyst 108, 1033-1050, 1983.

2. Houk R.S., V.A. Fassel, G.D. Flesch, H.J. Svec, A.L. Gray, C.E. Taylor. Inductively

Coupled Argon Plasma as an Ion Source for Mass Spectrometric Determination of Trace

Elements. Anal. Chem. 52, 2283-2289, 1980.

3. Houk R.S.. Mass Spectrometry of Inductively Coupled Plasmas. Anal. Chem. 58, 97A105A, 1986.

4. Heitkemper D.T., L.A. Kaine, D.S. Jackson, K.A. Wolnik. Practical Applications of

Element-Specific Detection by Inductively Coupled Plasma Atomic Emission

Spectroscopy and Inductively Coupled Plasma Mass Spectrometry to Ion

Chromatography of Food. J. Chrom. A. 671, 101-108, 1994.

5. Creed J.T., M.L. Magnuson, J.D. Pfaff, C.A. Brockhoff. Determination of Bromate in

Drinking Waters by Ion Chromatography With Inductively Coupled Plasma Mass

Spectrometric Detection. J. Chrom. A. 753, 261-67, 1996. 

6. Creed J.T., M.L. Magnuson, C.A. Brockhoff. Determination Of Bromate in the Presence

of Brominated Haloacetic Acids by Ion Chromatography With Inductively Coupled

Plasma Mass Spectrometric Detection. ES&T 31, 2059-2063, 1997.

7. Diemer J., K.G. Heumann. Bromide / Bromate Speciation by NTI-IDMS and ICP-MS

Coupled With Ion Exchange Chromatography. Fres. J. Anal. Chem. 357, 74-79, 1997.

8. Inductively Coupled Plasmas in Analytical Atomic Spectrometry, Second Edition,

copyright 1992 VCH Publishers, edited by Akbar Montaser and D.W. Golightly,

Chapter 12.

9. US EPA Method 200.8, Determination of Trace Elements in Waters and Wastes by

Inductively Coupled Plasma - Mass Spectrometry, Revision 5.4, 1994. Available from

the National Technical Information Service (NTIS) as PB-94-184942.

10. Carcinogens - Working With Carcinogens, Department of Health, Education, and

Welfare, Public Health Service, Center for Disease Control, National Institute for

Occupational Safety and Health, Publication No. 77-206, Aug. 1977. Available from

the National Technical Information Service (NTIS) as PB-277256.

11. Safety in Academic Chemistry Laboratories, American Chemical Society Publication,

Committee on Chemical Safety, 3rd Edition, 1979.

12. American Society for Testing and Materials. Standard Specification for Reagent Water,
321.8-20 

D1193-77. Annual Book of ASTM Standards, Vol. 11.01. Philadelphia, PA, 1991.

13. Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.
321.8-21 

TABLE 1. SPECTRAL AND CHROMATOGRAPHIC INTERFERENCES

Spectral Interferences

Interferent

Source

MASS

79

MASS

81

Plasma 40Ar38ArH+ 40Ar40ArH+

Sulfate* SO3H

+

Phosphate** PO3

+ PO3H2+

Potassium 40Ar39K

+

* Determined in 300 Fg/mL sulfate.

** Determined in 100 Fg/mL phosphate.

Potential Chromatographic or Coelution Interferences

 Retention Time*

Bromate 230

Bromoacetic Acid 170

Dibromoacetic Acid 460

Bromochloroacetic Acid 400

Bromide 570

Phosphate Matrix (PO3

+

) 180

Sulfate Matrix (SO3H

+

) 400

*Based on experimental conditions listed in Table 2. Reported in seconds to the

leading edge of the peak using the drift standard as t = 0.
321.8-22 

TABLE 2. EXPERIMENTAL CONDITIONS FOR THE DETECTION

 OF BROMATE VIA ICP-MS

ICP-MS Experimental Condition and Detection Limit

Instrument Upgraded VG Elemental PQ1

Power 1.4 KW

Cool Gas 12.0 L/min

Aux Gas 1.2 L/min

Nebulizer Gas 0.957 L/min (Concentric)

m/z Monitored 79 and 81

Analysis Mode Time Resolved or Chromatographic

Time Slice 0.4 seconds

Spray Chamber 5EC

Sensitivity (100Fg/L BrO3

 -) 35,000cps m/z 79

Background 

 (5mM HNO3 + 25mM NH4NO3 ) 100 cps m/z=79; 2500cps m/z=81

Detection Limit 0.3Fg/L

Chromatographic Experimental Conditions

Chromatograph Dionex Gradient GPM-2

Column PA100 Guard and Analytical

Flowrate 1 mL/min.

Pretreatment Cartridge On-Guard RP

Mobile Phase 5mM HNO3 + 25mM NH4NO3 (Isocratic)

Sample Loop 580 FL (based on i.d. and length)

Drift Standard Loop 170 FL
321.8-23 

TABLE 3. PRECISION AND RECOVERY DATA FOR BROMATE

 IN OZONATED DRINKING WATER*

WATER AVERAGE

CONCENTRATION

ng/mL

%RSD

Of AVG

CONC.

AVG%**

RECOVERY

LFM

%RSD

Of LFM

RECOVERY

1 22.2 5.5 97 3.6

2 3.0 6.4 98 1.4

3 10.1 3.6 98 3.4

4 2.7 5.1 96 3.8

5 1.3 10.6 96 3.0

6 0.8 15.5 102 2.4

 * n=5 for all analyses, determined using experimental conditions listed in Table 2.

** Fortified with 25Fg/L Bromate
321.8-24 

Abundance Sensitivity Considerations

for Bromate Analysis

Figure 1:

75 76 77 78 79 80 81 82 83

0

100

200

300

400

A) Borderline abundance sensitivity

Extrapolation

Line

75 76 77 78 79 80 81 82 83

0

50

100

150

200

250

300

B) Good abundance sensitivity

Extrapolation

Line
 321.8-25