326. 0-1

EPA Document # EPA 815-R-03-007

METHOD 326.0 DETERMINA TION OF IN ORGANIC OXYHALIDE DISINFEC TION

BY-PRO DUCTS IN D RINKIN G WATER U SING ION CHROM ATOGR APHY IN CORPOR ATING THE A DDITI ON OF A SUPPRESSOR ACIDIFIED POSTCOLUMN REAGENT F OR TRACE BROMATE AN

ALYSIS

Revision 1.0

June 2002

Herbert P. Wagne r and Barry

V. Pepic h, Shaw Environm ental Inc Daniel P . Hautma n and David J. M unch, US EPA, Office of G round Wate r and Drinking Water E. Salhi and Ur s von Gunte n, Swiss Fede ral Institute for Envir onment al Science and Technology, EAWAG,

CH-8600,

Dubendorf, Swit

zerland

TECHNICAL S UPPO RT CENTER OFFIC E OF GRO UND WATER AND DRIN KING W

ATER U. S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OHIO 45268326. 0-2 METHOD 326.0 DETERMINA TION OF IN ORGANIC OXYHALIDE DISINFEC TION BY-P RODUCTS IN DRINK

ING WATER

USING ION

CHROMATOG

RAPHY I

NCORPO RATING T HE ADDITION OF A SUPPRESSOR ACIDIFIED P OSTCOLUMN REAGENT FOR TRACE BROMATE AN

ALYSIS

1. SCOPE AN

D APP LICATION

1.1 Th is me th od co ve rs th e d et er mi na ti on of in or ga ni c o xyh al id e d is in fe ct io n b yproduct anions in reagent water, surf ace water, ground wa

ter, and finished drinking water. I

n addition, bromide can be accurately determined in source or

ra w w at er an d i t h as be en in cl ud ed du e t o i ts cr it ic al ro le as a d is in fe ct io n b yproduct precurs or. Bro mide conc entration in finishe d water c an diffe r due to numerous variables which can influence the c oncentration. Since this method, prior to the addition of the postcolumn reagent (PCR), employs the same hardware as EPA Method 300.1 (1) , the analysis of the c ommon anions (using EPA Method 300.1, Par

t A 1 ) can be

perfor med using

this instru

ment setup

with the po stcolumn hardware attached but “off- line” and with the appropriate smaller sample loop.

Inorganic Disinfection By-products by Conductivity Detection Analyte Comments
Bromate rep ort val ues > 15 .0 u g/L *
Bromide report v alues fr om source

and raw waters only
Chorite report v alues $ Minimum Reporting Level in calibration

range Chloride report v alues $ Minimum Reporting Level in calibration

range Inorganic Disinfection By-products by Absorbance Detection Analyte Comments
Bromate report v alues $ Mi ni mu m R epo rti ng Le vel to 15. 0 ug /L *
* the concentrations reported for bromate a ssume both detectors to be running si mu lt an eo us ly.326. 0-3

1.2 The single laboratory reagent water Detection Limits (Sect. 3.15) for the above analy tes are listed in Ta

ble 1. The

Detecti on Lim

it is defined as the

statistica lly calculated minimum concentration that can be measured w ith 99% confidence that the reported value is greater than zero. (2) The Dete ction L imit diffe rs from, a nd is lower than the Minimum Reporting Level ( MRL) (Sect. 3.16). The Detec tion Limit for a specific matrix may differ from those listed, depending upon the nature of the sample and the specific instrumentation employ ed.

1.2.1 In or

der to ac hieve comparabl e detec tion limits on the condu

ctivity detector, an ion chromatographic sy stem must utilize suppressed conductivity detection, be pr operly maintained a

nd must be capable of yielding a baseline with no more than 5 nanosiemen (nS) noise/drift per minute of monitored response over the background c onductivity.

1.2.2 In or

der to ac hieve ac ceptabl e detec tion limits on the postc olumn absorbance detector, the postcolumn reag ent must be delivered pneumatically and some f orm of software signal filtering or smoothing of the absorbance signal from the absorba nce detector must be incorporated.

1.3 This metho d is reco mmended f or use onl y by or under the super vision of a

naly sts 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 a ny of the above anions, a nion ident

ification should be

supporte d by

the use of

a fortif ied sample matrix cove

ring the anions of interest . The for

tification proced

ure is de scribed

in Section 9.8.

1.5 Users of

the metho d must demo nstrate t he ability to gene rate ac ceptabl e results with this method, using the procedures described in Section 9.

2. SUMMARY

OF METHOD

2.1 The development of this method was based upon the work of severa l investigators as summarised elsewhere. (3) A volume of sample, approximately 225 : L (see Note), is introduced into an ion chromatograph (I C) which includes a guard column, analytical c olumn, suppressor devices, conductivity detector, a postcolumn reagent delivery system (pneumatically

controlled), a heated postcolumn reaction coil, and a ultraviolet/visible (UV/Vis) absorbance dete ctor (see Figure 1). After

separation and suppression of the eluent, the oxy halide anions chlorite, chlorate, bromate >15.0 : g/L and bromide ar e measured using conductivity detection. To fa cilitate low-level detection of bromate, the suppress ed effl

uent fro m the cond

uctivity detector is combined with an acidic326. 0-4 solution of potassium iodide containing a cataly tic amount of molybdenum VI

. The mixture is heated at 80 B C (to fac ilitate c omplete r eaction ) where the broma

te reacts with iodide to form the tri-iodide ion which is measured by its UV absorpti on at 352 n

m.

NOTE: A 22 5 uL sa

mple loop c an be mad

e using a pproximate ly 111 cm (44 inches) of 0.02 inch i.d. PEEK tubing. The volume should be verified to be within 5% by weig

hing the sample loop empty, f illing the loop with deionized water and re-weighing

the loop assuming the density of water is 1 mg/uL.

3. DEFINITIONS

3.1 ANALYSI S BATCH – A sequence of samples, which are analyzed within a 30 hour per iod and inc lude no mor

e than 20 f

ield sampl es. An analy sis 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)

• Continuing

Calibrat ion Check

Standards (CCCs)

• Laboratory Fortified Blank (LFB)

• Laboratory

Fortified Sample Matrix (LFSM), and

• Either a

Field Du plicate ( FD) or a Laboratory

Fortifie d Sample Martix Duplicate (LFSMD).

3.2 SURROGATE ANALYTE (SUR) – A pure a nalyte, which c

hemically rese

mbles targe t analy tes and is extremely

unlikely to be foun

d in any sample. T

his analy te is added to a sample aliquot in known amount(s) before filtration or other processing and is measured with the same proc edures used to measure other sample components. The purpose of the SUR is to monitor method performance with each sample.

3.3 LABORATORY REAGENT B LANK (L RB) – An aliquot of reagent water or other bla nk matrix tha

t is treat ed exactl y a s a sample

including

exposure t

o all glassware, equipment, solvents and reag ents, sample preservatives, and surrog ates tha

t are use d in the analy sis batch . The L RB is used

to deter mine if method analy

tes or oth er inter

ferenc es are present in

the labor atory environment, the rea gents, or the app aratus.

3.4 LABORATORY FORTI FIED BL ANK (LFB ) – An aliquot of reagent water or other blank matrix to which known quantities of the method analy tes and all the preser vation co mpounds ar

e added in the lab oratory . The L

FB is analy

zed exactly like a sa mple, and its purpos e is to dete

rmine whe

ther the methodolo gy

is in control, and whet

her the l aboratory

is capab le of mak

ing acc urate a nd preci se measurements.326. 0-5

3.5 LABORATORY FORTI FIED SAMPL

E MATRIX (L

FSM) – An aliquot of an environmental sa

mple to whi ch known q

uantities of the method anal

yte s and all the preservation compounds are added in the labora tory. The L

FSM is analyzed exactly like a sa mple, and its purpos e is to dete

rmine whe

ther the sample ma

trix contributes bias to the analytica l results. The background concentra tions of the analytes in the sample ma trix must be determined in a separate aliquot and the

measure d values i

n the L FSM corr ected f or backg round co ncentra

tions.

3.6 LABORATORY FORTI FIED SAMPL

E MATRIX DUPLICATE (L FSMD) – A second aliquot of the field sample used to prepare the L FSM fortified, processed and ana lyze d identic ally . The L

FSMD is use d instead

of the Fi eld Duplic ate to access method precision when the occurr ence of target analy

tes is low.

3.7 LAB ORATORY DUPLICATES (L D1 and L D2) – Two

aliquots o f the same sample taken in the laboratory and analyzed sepa

rately with identical pr

ocedures. Analyses of L

D1 and LD2 indicate pre cision associated with laboratory procedu res, but n ot with sam

ple colle ction, pr

eserva tion, or storage p

rocedur es.

3.8 FIEL

D DUPLI CATES (FD1 and FD2) – Two separate samples collected at the same time

and plac e under i dentica

l circums tances, and trea

ted exact ly the same throughout field and laboratory procedures. Analy ses of FD1 and FD2 give a measure of the precision associated with sample collection, preservation, and storag e, as we ll as labor

atory procedu res.

3.9 STOCK STANDARD SOLUTI ON (SSS) – A concentrated solution containing one or more method analy tes prepared in the laboratory using assayed reference materials or purchased from a reputable commercial source.

3.10 PRIMARY DIL

UTION STANDARD (PDS) SOL UTION – A solution containing the analy

tes prepared in the laboratory from stock standard solutions and dilute d as need

ed to pre pare ca libration solutions a

nd other needed a

naly te solutions.

3.11 CALI

BRATION STANDARD (CAL ) – A solution prepared from the primary dilution sta

ndard sol ution and/

or stock s tandard

solution, a

nd the sur rogate analy tes. The C AL so lutions ar e used to c alibrate

the instru

ment resp onse with respect to analy

te concentration.

3.12 INSTRUMENT PERFORMANCE CHECK SOL UTION (I PC) – A solution of

one or mor

e method a

naly tes, surr ogates , or other

test substa

nces use d to evalu

ate the performance of the instrument sy stem with respect to a defined set of criteria.326. 0-6

3.13 CONTINUI

NG CALI

BRATION CHECK (CCC) – A calibra tion standard containi ng the me thod anal yte s and surr

ogates (s), whic h is analy zed perio dically to verify the acc uracy of the exist

ing cal ibration f

or those a naly tes.

3.14 QUALI TY CONTROL SAMPLE ( QCS) – A solution of method analytes and surrogate(s) of known conce ntrations that is obtained from a source external to the laborat ory and diff erent f rom the so

urce of calibra tion stand ards. I t is used to ch ec k s ta nd ar d i nt eg ri ty.

3.15 DETECTION L

IMI T – The minimum concentration of an analy te that can be identifie d, measur

ed and re ported with 99% confidenc e that the analy te concentration is greater than zero. This is a statistical dete rmination of precision (Sect. 9. 2.4), and accur

ate quan titation is n

ot expecte d at this le

vel. (2)

3.16 MINI

MUM REPORTING LEVEL (MRL) – The minimum concentration that can be reported as a quantitated value for a target analy

te in a sample following analysis. This defined c oncentration can be no lower than the conce ntration of the lowest continuing

calibra tion stand ard for that ana lyte and can only be used if accept able qua lity control c riteria for this st

andard a re met.

3.17 MATERIAL

SAFETY DATA SHEET (MSDS) – Written information provided by v endors c oncerni

ng a ch emical’ s toxicity , health hazards, phys ical pro perties, fire, a nd reactivity

data inc luding st

orage , spill, and handling precau tions.

4. INTERFER

ENCES

4.1 Interfere

nces can be divided into three different ca tegories: direct chromat ographic coel

ution, whe

re an analy

te response is obse

rved at v ery

nearly the same retention time as the target anion; conce ntration dependant coelution, which is observed when the response of highe r than typical conc entrations of the neighb oring pe ak overl ap into the retention window o f the tar get ani on; and, ionic character displacement, where retention times may signif icantly shift due to the influenc e of hig

h ionic str

ength ma trices ( high mine

ral cont ent or ha rdness) overloading the exchange sites on the column and sig nificantly shortening

target analyte' s retention times.

4.1.1 A direct

chromat ographic coel

ution may be solved

by c hangin g column s, eluent str ength, modify

ing the e luent with

organ ic solven ts (if com patible with IC columns), changing the detection systems, or sele ctive removal of the interference with pretreatment. Sample dilution will have little to no effect. The analy

st must verify that these cha nges do not induce any negative affects on method perf ormance by

repeating and passing all the QC criteria as described in Section 9.326. 0-7 4.1.2 Sample dilu

tion may resolve some of th e diffic

ulties if the interf

erence is the result of either concentration dependant coe lution 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 considera tion of project objectives should be given prior to pe

rforming such a dil

ution. An a

lternati ve to samp le dilution, may be dilution of the eluent as outlined in Section 11.2.6.

4.1.3 Pretrea

tment car tridge s can be e ffectiv e as a me ans to elim inate ce rtain matrix inter

ferenc es. With an

y pr oposed pr etreatment, the a

naly st must verify that tar

get analy te(s) are not affected by

monitoring recovery

after pretr eatme nt. W ith ad vances in ana lytical s eparat or col umn t echno logy which emp loy

higher capaci ty a nion excha

nge re sins, the need for

these cartridges has been g

reatly re duced.

4.2 Method interferences may be caused by

contaminants in the reagent water, reage nts, gla ssware, and other

sample pr

ocessing appara tus that le ad to discrete artifacts or elevated baselines in an ion chromatog ram. These interferences ca n lead to f alse posi tive resu lts for ta rget a naly tes as we ll as redu

ced dete ction limits as a consequence of elevated ba seline noise.

4.3 Samples that contain particles larger than 0.45 microns and r eagent solutions require filtration to preve

nt damag e to instru

ment colu mns and fl ow sy stems.

4.4 Close attention should be given to the potential for carry over peaks from one analysis which will aff

ect the proper detection of analy tes of interest in a second or subsequent analy sis. Normally, in this analy sis, the elution of sulfate (retention time of 17.5 min.) indicates the end of a chromatogra phic run, but in the ozonated and chlorine dioxide matrices, 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 rec ommended to allow for the proper elution of any potentially

interfering late peaks. I

t is the responsibility of the user to confir m that no la

te eluting peaks ha ve carr ied over into a subs equent a

naly sis thereby compromis ing the i

ntegri ty o f the ana

lyti cal res ults.

4.5 Any residual c

hlorine dioxide present in the sample will result in the formation of additiona l chlorite prior to a naly sis. I f residual chlor

ine dioxide

is suspec ted in the sample, the sample must be sparged with an inert g as (helium, argon or nitrogen) for approximately five minutes. This sparging must be conducted prior to ethylenediamine pre servation and at the time of sample collection.

4.6 The presence of chlorite can inter fere with the quantitation of low concentrations of bromate on the postcolumn UV/Vis absorbance detector. In or der to ac curate ly326. 0-8 quantify bromate concentrations in the range 0.5 - 15.0 : g/L in this postc olumn sys tem, the excess chlorite must b e remove d prior to analy sis as outli

ned in Section 11.1.4.

5. SAFETY

5.1 The toxicity or carcinog enicity of ea ch reagent used in this method has not been precise ly d

efined; each chemical c ompound should be tr eated a s a potent

ial healt h hazard, a nd exposure

to these c

hemicals should be m

inimized. The labora

tory is responsible for maintaining a current awa reness file of OSHA regulations regarding the safe

handling of the chemicals specified in this method. A refe rence file of MSDSs should also be made available to all personnel involved in the chemical analy sis. Additional references to laboratory safety a re available. (4-7)

5.2 Pure standard materials and stock standards of these compounds should be handled w

ith suitabl e protection to skin a nd ey es. Care should be t

aken not t o breathe the vapor

s or inge st the mate

rials.

5.3 The following chemical has the potential to be highly toxic or hazardous. The Material Safety

Data Sheet (MSDS) should be consulted.

5.3.1 Sulfuric acid – used to prepare reg enerant solution (Sect. 7.1.8) for the second suppressor (Dionex AMMS or Ultra ASRS-1 used in the chemical mode) an d to for pr

etreatment of the

samples f

or chlor ite remov al (Sect

. 7.1.7, 11.1.4)

6. EQUIPME NT AND SUP PLIES

6.1 ION CHROMATOGRAPH – Analy tical system complete with ion chromatographic pump and all required a ccessories including sy

ringes, analy

tical columns, compressed gasses, suppressors , conductivity detector, mixing “tee ”, postcolum

n reag ent deliv ery

sys tem, rea

ction coi l, reac tion coil he ater, UV /Vis absorbance detector (Fig

ure 1) and a computer- based data acquisition and control sys tem.

NOTE: Becau se the KI PCR solution is susceptible to oxidation, resulting in a yellow colored solution, the PCR MUST be flushed from the suppre ssor, reaction coil and detector cell with reage nt water upon completion of the final analysis and prevent ed from d raining through the rea ction coi l by

gravit y on ce the sy stem is shut down. This can be a ccomp lish ed eit her man ually or b y incorpo ratin g a column switching valve in combination with a reagent wa ter flush.326. 0-9 6.1.1 ANION GUARD COL UMN – Dionex AG9-HC 4 mm (Cat.#: 51791or equivalent). This column functions as a protector of the separa tor column. If omitted from the sy

stem the retention times will be shorter.

6.1.2 ANI ON SEPARAT OR COL UMN – Dionex AS9-HC c olumn, 4 mm (Cat.#: 51786 or equivalent, see Note). The AS9-HC, 4-mm column using the condi tions outlined in Table 1 produce d the sepa rations sh own 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- mmcolumns. This reduced injection volume would decrease the “on-column” bromate and negatively

affect PCR reactivity and the subsequent absor bance response. As well, the 2-

mmcolumns r

equire a flow rat e approximately

4 times les s than the

4-mm columns. At the lower flow rates, band broading may become an issue and it would be difficult to accurately maintain the appropriate reduced flow rate fo r the PCR.

6.1.3 ANION SUPPRESSOR DEVICES – The data presented in this method were generated using

a Dionex Ultra-1 Anion Self Regenerating Suppressor (4 mm ASRS, Cat.#: 53946) for electrolytic suppre ssion of the eluent a nd a seco nd Ultra - 1 ASRS was us ed in the c hemical m

ode to acidify the PCR just prior to addition to the mixing tee

. Equivalent suppress or devic es may

be utilized

providing

compara ble condu ctivity detection limits are achieved and adequate ba seline stability is attained as measured by

a combined baseline drift/noise of no more than 10 nS per minute over the background conductivity . Alternative suppressor evaluations subsequent to this method development work have indicated that improved detection limits and precision and accuracy can be obtained for bromate by

conductivity detection (8) . If conductivity analytes below 10 ug/L are to be

reported, the combined baseline drift/noise will be required to be no greater tha n 5 nS per minute over the background

co nd uc ti vi ty. The suppressor must be able to withstand approximately 80 -120 psi ba

ck press ure whic h results f rom conne cting th e postcol umn hardware to the “eluent out” port of the suppre ssor. The suppressor used to acidif y th e PCR must be

capable of contin uous oper ation usin g 150 mN sulfuric acid as t he reg eneran

t.

6.1.3.1 – T

he condu ctivity suppress or was se

t to perform elect

roly tic suppression at a current setting of 100 mA using the e xternal water mode. Insufficient baseline stability was observed on the conductivity detector using an ASRS in recyc le mode.326.0-10 6.1.4 CONDUCTIVI TY DETECTOR – Conductivity cell (Dionex CD20 or equivale nt) capable of providing data as re quired in Section 9.2.

6.1.5 ABSORBANCE DETECTOR – Absorbance detector (Dionex AD20 or equivale nt with 10- mmcell pathlength, equipped with a deuterium source bulb, or equivalent and capable of measuring absorbance at

352 nm) capable of providing data as re quired in Section 9.2.

6.1.6 POSTCOLUMN REAGENT DEL IVERY SYSTEM –Delivery system (Dionex PC-10 or equivalent) capable of pneumatically deliver

ing the postcolumn reagent to the “eluent in” port of the suppre ssor to acidify the PCR prior to

enterin g the mixing

tee (se e Note). The pre ssure settings wi ll need to be established on an individual basis for each specific instrument configuration and at a level which y ields the prescribed PCR flow rates.

NOTE : Since KI is photosensitive, the KI /Mo PCR solution was observed to develop a light yellow color with time, even when stored under helium in the opaque plastic PC-10 delivery container inside the PC-10 pressurization vessel. Purging the KI /Mo solution with helium immediate ly a

fter pre paratio n to remov e all oxy gen did not comple

tely eliminate the problem. Consequently, in orde r to facilitate overnight (24 hours) operation, the external wall of the PC-10 plastic pressurization vessel was wrapped with an opaque tape, or othe r light impervious material, to prevent any

light exposure to the KI/Mo PCR (care must be exercised to leave about 1/16 th of an inch at both the top and bottom of the vessel free of tape to allow for proper sealing of the top and bottom . The generation of the tri-iodide ion is pH dependant and the se cond suppressor is used to a

cidify the PCR just b efore e

ntering the rea ction coi l. Prior to initiating any ana

lysis batch, to ensure that the pH of the reaction mixture is below 2, the effluent from the absorbance dete ctor should be monitored using pH test strip s.

6.1.7 REACTION COI

L – 500-uL

internal volume, knitted, potted and configured to fit securely

in the postcolumn reaction coil heater. (Dionex Cat.#: 39349 or equivalent).

6.1.8 POST COLUMN R EACTION COIL HEATER – Capa ble of maint ainin g a temperature of 80 °C (Dionex PCH-2 or equivalent).

6.2 DATA SYSTEM – The Dionex Peaknet Data Chromatography Software was used to gene rate all the data in the atta

ched tab les. Othe

r compute

r-base d data sy

stems may achieve approxima

tely the same Detecti on Lim

its, but the use

r must demonstrate this by the proc edure outlined in Section 9.2.326.0-11

6.3 ANALYTI CAL BAL ANCE – Used to accurately weigh target analy

te salts for stock standard preparation (±0.1 mg sensitivity ).

6.4 TOP LOADI

NG BALANCE – Used to a ccurately weigh reagents to prepa

re eluents (±10 mg sensitivity).

6.5 WEIGH

BOATS – Pl astic, dis

posable, used to we igh elue nt reag ents.

6.6 SYRINGES – Plastic, disposable, 10 mL, used dur ing sample preparation.

6.7 PIP ETS – P ast eur , pl ast ic o r gl ass , di spo sab le, gra dua ted , 5 m L and 10 m L.

6.8 BOT TLES – Op aqu e, h igh den si ty po lyet hyle ne ( HDP E) o r am ber gla ss , 30 mL, 125 mL, 250 mL - use d for sample collection and storage of c alibration solutions. Opaque bottles are required due to the photorea ctivity of the chlorite anion.

6.9 MICRO BEAKERS – Plastic, disposable, used during sample pr eparation.

6.10 PARTICULAT E FILTERS – Gelman ion chromatography Acrodisc 0.45 um (Cat.#: 4485 or equivalent) syr inge filters. These cartridg es are used to remove particulates and [Fe(OH) 3(s) ] which are formed during the oxidation-reduction reaction betwee

n Fe (I I) a nd ClO 2 - (see Sect. 11.1.4).

6.11 HYDROGEN CARTRIDGES – Dionex OnGuard-H cartridges (Cat.#: 039596 or equivalent). These cartridges a re conditioned according to the manufac turer’s directions and are used to protect the analy tical column and the suppressor membran e by

removing

excess fe rrous iron [Fe (I

I)]. T he ferr ous iron is

added to field samples to reduce chlorite levels prior to analy sis of chlorine dioxide disinfected water samples for trace le vels of bromate (see Sect. 11.1.4).

7. REAGENTS AND STANDARDS

7.1 REAGENTS AND SOLVENTS – Reag ent grade or better chemica ls should be used. Unless otherwise indicated, it is intended that all reagents shall conf orm to the specifications of the Committee on Analy tical Reagents of the American Chemical Society, wher

e such specifications are available. Other grades may

be used, provided it is f

irst dete rmined tha

t the rea gent is o f suffic iently

high pur ity to permit its use without lessening the quality of the de termination.

7.1.1 REAGENT WA

TER – Distil led or de ionized wa ter 18 M S or better, free of the anions of interest. Water should contain particles no large r than 0.20 microns.326.0-12 7.1.2 ELUENT SOL

UTION – Sodium carbonate ( CAS#: 497-19-8) 9.0 mM. Dissolve 1.91 g sodium carbonate (Na 2 CO 3 ) in rea

gent wa ter and d ilute to 2 L.

7.12.1 This eluent solution must be sparged for 10 minutes with helium prior to use to remove dissolved gases which may form micro bubbles in

the I C compromi sing sy

stem perf ormance and adve rsely effecting the integrity

of the data. Alternatively , an in-line degas apparatus may

be employed.

7.1.3 ETHYLENEDI

AMINE (EDA) PRESERVATI ON SOLUTI ON (100 mg/mL) – Dilute

2.8 mL of ethy lenedia mine (99% ) (CAS#: 10 7-15-3)to 25 mL w it h r ea ge nt wa te r. Pr ep ar e f re sh mo nt hl y.

7.1.4 AMMONIUM MOL YBDATE SOLUTI

ON – A 2.0-mM solution of ammonium molybdate tetrahy drate [(NH 4 ) 6 Mo 7 O 24 ·4H 2 O, CAS#: 12027667, Fluka Cat.#: 09878 or equivalent] is prepared by dissolving 0.247 g in 100 mL of reag ent water. This reagent is stored in an opaque pl as ti c s to ra ge bo tt le an d p re pa re d f re sh mo nt hl y.

7.1.5 POSTCOL

UMN REAGE

NT (0.26 M

KI, 4 3 uM ammoni

um moly bdate heptahydra

te) –The postcolumn reagent is prepare d by adding 43.1 g of potassium i odide (K

I, CA S#: 7681110 , Fluka Ca t.#: 60400 or equiva

lent) to a 1-L volumetric flask containing about 500 mL of reag ent water. Two hundred and fifteen μ L of the ammonium moly bdate solution (Sect. 7.1.4) is added to the volumetric flask and diluted to volume with reagent water

. The PCR is sparged with helium for 20 minutes to remove all traces of dissolved oxygen and immediately placed in the PC-10 delivery vessel and pressur ized with he lium. The r

eage nt is stable

for 24 hou

rs if prop erly protected from light (Sect. 6.1.6).

7.1.6 FERROUS IRON SO LUTION [1000 mg/L Fe (II )] – Dissolve 0.124 g ferrou s sulfate

heptahy drate (FeSO 4 .7H 2 O, CAS#: 7782630, Sigma Cat. #: F-7002 or equ ivale nt) in appro xim ately 15 m L reagent w ater co ntain ing 6 uL of concen trated n itric ac id and dilu

te to 25 mL

with rea gent wa ter in a volumetric flask (final pH

- 2). The Fe (II ) solution must be prepared fresh e very two day s.

7.1.7 SULF URIC A CID ( 0.5 N) – D ilute 1.4 mL of conce ntrated sulfuric acid (Fi she r Sc ien ti fic Cer ti fie d AC S P lu s, A 300 -50 0) t o 10 0 m L.

7.1.8 SULF URIC A CID ( 0.15 N) – D ilute 8.5 mL of conce ntrated sulfuric acid (Fi she r Sc ien ti fic Cer ti fie d AC S P lu s, A 300 -50 0) t o 20 00 m L.326.0-13

7.2 STANDARD SOLUTI ONS – Standard Solutions may be prepar ed from certified,

commerc ially

availab le solution s or from s olid compo unds. Compo

unds used to prepare solutions must be 96% pure or grea ter and the weight may

be used without correction for purity to calculate the concentration of the stock standard. Solution concentrations listed in this section were used to develop this method and are included as an example. Even though stability times for standard solutions ar e suggest ed in the following sectio ns, laborat ories shoul d use standard QC practic es to det ermine when Standard So lutions desc ribed in this sect ion need to

be replac ed.

7.2.1 ANAL

YTE STAND ARD SOL

UTIO NS (1000 mg/L) – Stock standard solutions ma

y be purchas ed as ce

rtified s olutions or

prepar ed from A CS reage nt grad e, potass ium or sodiu

m salts as l isted below, for mos t analytes. Certifie d chlorite standard solutions are commercially available. If these are

not used, chlorite requires careful considera tion as outlined below in Section 7.2.1.1.4.

7.2.1.1 ANALYTE STOCK STANDARD SOL UTIONS – I

ndividual Analyte Stock Standards Solutions are pre pared as described below.

7.2.1.1.1 Bromide (Br

- ) 1000 mg/L – Dissolve 0.1288 g sodium

bromide (NaBr, CAS#: 7647-15-6) in reag ent water and dilute to 100 mL in a volumetric flask.

7.2.1.1.2 Bromate (BrO 3 - ) 1000 mg/L – Dissolve 0.1180 g of

sodium bromate (NaBrO 3 , CAS#: 7789-38-0) in reagent water and dilute to 100 mL in a volumetric flask.

7.2.1.1.3 Chlorate (C1O 3 - ) 1000 mg/L – Dissolve 0.1275 g of

sodium chlorate (NaC1O 3 , CAS#: 7775 -09-9) i n reage nt water and dilute

to 100 mL

in a volume

tric flask.

7.2.1.1.4 Chlorite (C1O 2 - ) 1000 mg/L – Prepare from commercially a

vailable standards or as described below. If the amperometric

titration of the technical grade sodium chlorite (NaC1O 2 ), as spe cified in the Note below, had indicated the purity of the salt to be 80.0 % NaC1O 2 , the analyst would dissolve 0.1676 g of sodium chlorite (NaC1O 2 , CAS#: 7758-19-2) in reagent water and dilute to 100 mL in a volumetric flask.326.0-14 Note: High pur

ity s odium chlorite (Na

ClO 2 ) is not currently c ommercially ava ilable due to its potential explosive instability. Recrystallization of the technical grade (approx. 80%) can be pe rformed but it is labor intensive and time consuming. The simplest approach is to deter mine the exact purity

of the Na ClO 2 using the iodometric titration procedure. (9) Following titration, an individual component standard of chlorite must be analyzed to determine if

there is any sig

nificant contamination (g

reater than 1% of

the chlor ite weig ht) from chlorate, bromate or bromide (as other method target anions) in the technical gr ade chlorite standard.

7.2.1.2 ANAL

YTE PRI MARY DI

LUTI ON STAND ARD (Ana

lyte PDS) SOLUT ION

– Prepar e two Ana

lyte PDSs by diluting the Analy

te Stock Stand

ard Soluti ons with re agent water containing EDA (at a final concentration of 50 mg/L ) in volumetric glassware. The dilutions used to prepare these solutions during the method development studie s are pr ovided be low as an

example. Pr

ior to using mixed standards for calibration or spiking solutions, ensure that the in

dividual A

naly te Stock Sta

ndard Solu

tions do not

contain any appre ciable concentrations of the other targ et analytes. Dilutions of these Analyte PDSs, refe rred to as Solution A and B below, are used to prepare the ca libration solutions (Sect. 7.2.3) and the c ontinuing

calibra tion chec k solutions

(Sect. 10 .3) for b oth detectors.
Analyte PDS Solution A
Analyte Initial Conc.

(mg/L) Volu me

(mL) Final Volu me

(mL) Final Conc.

(mg/L) Chlorite 1000 2.5 25 100 Bromide 10000 0.25 25 100 Chlorate 1000 2.5 25 100

Analyte P

DS Solution B
Analyte Initial Conc.

(mg/L) Volu me

(mL) Final Volu me

(mL) Final Conc.

(mg/L) Bromate 1000 1.0 100 10326.0-15 7.2.2 SURROGATE ANALYTE (SUR) SOL UTION, DI CHLOROACETATE (DCA, CAS#: 19559-59-2 )

7.2.2.1 SURROGATE STOCK SOLUTI ON (0.50 mg/mL) – Prepa re a surrog ate stoc k solution by di ssolving 0.065 g o f dichlor

oacetic acid, pot assium sal

t (Cl 2 CHCO 2 K) in rea

gent wa ter and d iluting to 100 mL in a volume

tric fla sk. This sol

ution is use d to fortif

y a ll field sampl es, QC sampl es and calib ratio n stan dards by adding a 20-uL aliquot of the Surroga te Stock Solution to 10 mL of the sample. This solution must be prepared fresh every 3 months or sooner if signs of degra dation ar e prese nt.

7.2.2.1.1 Dichloroacetate is potentially present in treated drinking waters as the acetate of the org anic disinfection byproduct, dichloroa

cetic acid (DCAA). Ty

pical concentrations of DCAA rarely exceed 50 : g/L, which would represent only

a five percent increase in the observed response over the fortified conc entration of 1.00 mg/L . Conseque

ntly , the uppe

r recov ery

limit for the surr ogate (90% to 115%) has been increased to allow for this potential background.

7.2.2.1.2 If the analy

st is exclusively interested in monitoring tra ce b rom ate usi ng t he P CR and th e UV /VIS absorba nce dete ctor, sup

pression of the el uent prio r to
rea cti on w it h t he P CR MUS T be in cor por ate d. In addition, the surrogate must also be included and meet the QC requirements as outlined in Section 9.7.1.

7.2.2.2 SURROGATE PRIMARY DIL UTION STANDARD – A Surrogate PDS is not prepared since the Surrog ate Stock (Sect 7.2.2.1) is used to fortify samples.

7.2.3 CALI

BRATION STANDARDS (CAL ) – At least 5 calibration

concen trations a re requ ired to pr epare t he initial calibra tion curv e (Sect. 10.2) for each detector. Prepar e the calibration standards over the concentration range of intere st from dilutions of the Analyte PDSs A and B in reagent water c ontaining EDA (50 mg/L). The lowest concentration calibration standard must be at or below the MRL , which may depe nd upon system sensitivity . The calibration standards for the development of this method

were pr epared by a dding a liquots of t

he two Ana

lyte PDSs (Analyte PDS Solution A and B desc ribed above in Sect. 7.2.1.2) as shown in the tables below to a volumetric flask, containing the listed volume of326.0-16 EDA solution, and diluting to volume with reagent water. These standards may be also be use d as CCCs.

Conductivi

ty Dete ctor CA

L and CCC Sta ndards

Cal Std. Stock

A (μ L) Stock

B (μ L) EDA Volume (uL) Final Volume (mL) ClO 2 , Br, C lO 3

Final Conc. (μ g/L) Bromate

Final Conc. (μ g/L) 1* 10 100 50 100 10 10 2 25 250 50 100 25 25 3* 75 500 50 100 75 50 4 200 750 50 100 200 75 5* 500 1000 50 100 500 100
*Prepar ed in lar ger vo lume and u sed as CCCs

Absorbanc e Dete ctor CA L and CCC Sta ndards

Cal Std. Stock B (μ L) EDA Volume (uL) Final

Volume (mL) Bromate

Final Conc. ( μ g/L) 1* 5 50 100 0.5 2 10 50 100 1.0 3 20 50 100 2.0 4* 50 50 100 5.0 5 100 50 100 10.0 6* 150 50 100 15.0
*Prepar ed in lar ger vo lume and u sed as CCCs

7.2.3.1 Fortify e ach CAL or CCC standard by adding a 20 uL aliquot of the Surro gate Sto ck Standa rd Solution

(Sect. 7. 2.2.1) to a

20 mL disposable plastic micro beaker containing 10.0 mL of the calibration standard (or CCC) and mix. These volumes may be adjusted to meet spe cific la

borator y a utosample

r volume require ments.326.0-17

8. SAMPLE COLL ECTION, PRE SERVATIO N AND STORA GE

8.1 SAMPLE COLL

ECTION

8.1.1 Samples should be co llected i n opaque plastic or amber g lass bottle s. All bottles must be thoroughly clea ned and the volume collected should be sufficie nt to ensur

e a repr esentat ive sample , allow for replic ate ana lys is and laboratory

fortified matrix analysis, if require d, while minimizing waste dis posal.

8.1.2 When collecting a field sample from a treatment plant employ ing chlorine dioxide, the field sample must be sparged with an inert gas (he lium or nitroge n) prior to addition

of the ED A prese

rvative at time of

sample collecti on. The sa

mple shoul d be colle cted in a clean wide mouth f

lask (such as an Erlenmey

er flask). The sparging

gas can be obtained by

using a lecture bottle of nitrogen or helium fitted with a reg ulator and connected to a disposable glass Pasteur pipette with PVC tubing. The gas flow should be adjusted to produce a steady flow of bubbles. After 10-15 minutes of sparging, all traces of c hlorine dioxide should be removed from the sample. It can then be pour ed from the flask into the sample bottle that contains the ethy lenedia mine (EDA

) prese rvative . In order to e liminate potential cross contamination problems, it is recommended that a clean Erlenmeye

r flask and a new disposable pipette be used at ea ch sampling point.

8.1.3 Add a sufficient volume of the EDA preservation solution (Sect. 7.1.3) 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.

8.2 SPECIAL SAMPL ING REQUI

REMENTS AND PRECAUTIONS FOR CHLORI TE

8.2.1 Sample bottles used for chlorite analy sis must be opaque plastic or amber glass to protect the sample

from lig ht.

8.2.2 When preparing the L FSM, be aware that chlorite is an oxidant and may react w ith the na tural organic matt

er in an u ntreate d drinking

water ma trix

as a res ult of oxidat

ive dema nd. I f untrea

ted wate r is colle cted for

chlorite analysis, and subseque

ntly used for the L

FSM, EDA preservation will not control this demand and reduced chlorite recove ries may be obse

rved.326.0-18 8.2.3 Chlorite is

suscepti ble to deg radatio n both thro

ugh ca taly tic reac tions with dissolved iron salts and reactivity towa rds free chlorine which exists as hypochlorous ac id/hypochlorite ion in most drinking water as a residual disinfectant. (10) EDA serves a dual purpose as a prese rvative for chlorite by chelating iron as well as any other cataly

tically destructive meta

l cations and removing hy

pochlorous acid/hypoc

hlorite ion by forming a

n organochloramine. EDA preser vation of chlorite also preserves the integr ity o f chlora

te which c an incre ase in unpreserv ed sample s as a re sult of chlor ite deg radatio n. EDA al so prese rves the integr ity o f bromate concentrations by

binding with hypobromous ac id/hypobromite ion which is an intermediate formed as a by -product of the reaction of either ozone or hypochlorous ac id/hypochlorite ion with bromide ion. I f hypobromous acid/hypobromite ion is not removed fr om the matrix, further reactions may form bromate

ion.

8.3 SAMPLE SHIPMENT AND STORAGE – All samples must be chilled during shipment and must not exceed 10 o C during the first 48 hours after collection. Samples must be confirmed to be at or below 10 o C when they ar e received at the laboratory. Samples store d in the lab must be held at or below 6 o C and protected from light until analysis. Samples should not be frozen. Sample pre servation and holding t imes for t he anions are as f ollows:

Analyte Prese rvation Holding Time
Bromate 50 mg/L EDA, store at < 6 o C 28 da ys Chlorate 50 mg/L EDA, store at < 6 o C 28 da ys Chlorite 50 mg/L EDA, store at < 6 o C 14 da ys Bromide* 50 mg/L EDA, store at < 6 o C 28 da ys *S ou rc e a nd ra w w at er on ly.

9. QUALITY CO NTROL

9.1 Each laboratory

using this method is required to operate a formal quality control (QC) program. The requireme nts of this program consist of an initial demonstration of laboratory capability (I

DC), and subsequent analy sis in each Analysis Batc

h (Sect. 3.1) of a Labor

atory Reagent Blank (LRB) , Continuing Calibration Check Standards (CCCs), Laboratory Fortified Blank (L

FB), Instr ument Per

formanc e Check St

andard (IPC), Laboratory Fortifie d Sample Matrix (L FSM) and

either Laboratory

Fortifie d Sample Ma

trix Duplica

te (LF SMD) or a

Field Du plicate ( FD) Samp le. This se ction det ails the sp ecific326.0-19 requirements for each of these QC par ameters for both the conductivity and absorbance detectors used in this application. Althoug h the Dete ction L imits and MRLs may

differ, the QC requirements and acceptance criteria are the same for both detectors. The QC criteria discussed in the following sec tions are summarized in Section 17, Tables 4 and 5. These criteria are conside red the minimum ac ceptabl e QC crite ria, and laborat ories ar e encou raged to institute additiona l QC prac tices to me et their s pecific needs.

9.2 INI TIAL

DEMONSTRATION OF CAPAB ILITY (I DC) – Requirements for the Initial Demonstration of Capability are described in the following sections and summarized in Section 17, Table 4.

9.2.1 INI TIAL

DEMONSTRATION OF L OW SYSTEM BACKGROUND – Befor e any field sam ples are analy zed, and a

ny t ime a new

set of re agents is used, it m

ust be demonstrate d that a la borator y r eage nt blank is reasonably

free of contamination and that the criteria in Section 9.4 ar e met.

9.2.2 INI TIAL

DEMONSTRATION OF ACCURACY – Prior to the ana lysis of the IDC samples, verify

calibration accuracy

with the preparation and analy sis of a mid

-level Q CS as defined in Sect ion 9.11. If the ana

lyte

recove ry is not + 15% of the

true val ue, the a ccurac y of the metho d is unacceptable. The source of the pr oblem must be identified and corrected. After the accuracy

of the calibration has been verified, prepa re and analy

ze 7 replicate LFB s fortified at a recommended concentra tion of 20 ug/L for the conductivity detector or near the mid-range of the initial calibration curve. F or the ab sorbanc e detec tor, pre pare 7 r eplicate LFB s fortifi ed at a recommended concentration of 2.0 ug/L bromate. Sample preservatives as descri bed in Secti on 8.1 .3 mu st be a dded t o all LFBs . The av erage recovery of the replicate values must be within ± 15% of the true value.

9.2.3 INI TIAL

DEMONSTRATION OF PRECI SION – Using the same se t of replicate data genera

ted for Section 9.2.2, calculate the standard deviation and percent relative standard deviation of the r eplicate recoveries. The percen t relative standa

rd devia tion (%RSD ) of the r

esults of t he repli cate analyses must be # 20%.

9.2.4 DETECTION LI

MIT D ETERMI

NATI ON – Prep are and

analy ze at leas t 7 replica te LF Bs at a c oncentr

ation esti mated to b e near t

he Dete ction L imit over at l east 3 da

ys u sing the

procedu re described in Se ction 11. T his fortification level may

be estimated by sele cting a concentration with a signal o f 2 to 5 time s the noise level. The approp

riate co ncentra tion will be depe ndent upo n the sens itivity of the I C sys tem being

used. Samp le326.0-20 preser vatives a s descri

bed in Section 8.1.3 m

ust be add

ed to thes e samples. Calculate the Detection Limit using the e quation

Detecti on Lim

it = St ( n - 1, 1 - alpha = 0.99)
where t (n-1,1-alpha = 0.99)

= Student's t value for the 99% confidence le vel with n-1 degre es of fr

eedom, n = number of replicates, and S = standa

rd devia tion of re plicate a naly ses.

NOTE: Calculated Detection Limits need only be less than 1 / 3 of the laboratory’ s MRL to be considered acc eptable. Do not subtract blank values when performing Detection Limit calculations. The Detection Lim it is a s ta ti st ic al de te rm in at io n o f p re ci si on on ly. (2) No precision and accuracy criteria are specified.

9.3 MINI

MUM REPORTI

NG LE VEL ( MRL) – The MRL

is the thre shold

concen tration of an analy te that a l aboratory

can expec

t to accu rately quantita te in an unknow

n sample. The MRL

should not b e establ ished at a n analy te concentration that is less than either three times the Detection L imit or a

concen tration w hich woul d yi eld a re sponse le ss than a s ignal- to-noise (S/N) ra tio of five. Dependi

ng upon t he study ’s data q

uality objectiv es it may

be set at a higher concentration. The lowest c alibratio n standard m ust be at or below the MRL and therefore, the MRL must never be established at a concentrat ion lower than the lowest calibration standard

.
9.4 LABORATORY REAGENT B LANK (L RB) – A LRB is require d with each Analysis Batc

h (Sect. 3.1) of samples to determine any background sy stem contamination. I f within th e reten tion time wi

ndow of a ny a naly te, the L RB produces a peak that would prevent the deter mination of that analyte, dete rmine the source of contamination and eliminate the interfere nce before processing samples. Background contamination must be reduc ed to an acceptable level before proceeding. B ackground from method analy tes or contaminants that interfere with the measurement of method analy tes must be below 1/3 the MRL. If the targ et analytes a

re detected in the LRB at concentrations equal to or grea ter than this le

vel, then all data f or the pr oblem ana

lyte (s) must be

consider ed invali d for all samples in the analy sis batch.

9.4.1. EDA must be added to the LRB at 50 mg /L. By including EDA in the LRB, any potential background contamination from the EDA will be identified.326.0-21 9.4.2 When the PCR method is used for low level bromate analy sis on samples from public water sy stems (PWSs) which employ chlorine dioxide disinfection, the ma

trix must be pretrea

ted to re move the p otentiall

y interfering chlorite anion (Sect. 11.1.4). When these ty pes of pretreated samples, or any ty

pe of pretreatment is applied to field samples included as part of an analy sis batch, a second LRB must be pre pared, pretreated and analyzed to confirm no ba ckground effects of the pre treatment are present. If t he an al ysi s b at ch co nt ai ns on ly p re tr ea te d s am pl es , t he n o nl y a pretreated LRB is required.

9.5 CONTINUI

NG CALI

BRATION CHECK (CCC) – CCCs are prepa red in the same manner as the Calibration Standards (Sect. 7.2.3), using re agent water and EDA as described in Section 8.1.3. They are analy zed during an analy sis batch at a required frequency

to confirm that the instrument meets initial calibration criteria. See Section 10.3 for concentration re quirements, frequency requirements, and acceptance criteria

.
9.6 LABORATORY FORTI FIED BL ANK (LFB ) - A LFB is required with each analysis batch to conf

irm acceptable method accurac y. Since calibra

tion solutions are prepared in larg e volumes and can be used over an extended period of time, the integ rity of the concentra

tion of the

solution us ed to for

tify the LFSM is checked by

preparing the L

FB using the same Analy te Stock Standard Solutions used to prepare the L

FSM fortification solution. The fortified concentration of the LFB should be rotate d between, low, medium, and high concentrations from ba tch to batch. The low concentration L FB must be as near as practica l to, but no more than two times the MRL. Similarly, the high concentration should be near the high end of the c alibrati on rang e establ ished dur ing the i nitial ca libration (Sect. 10.2). The recovery

of all analytes f

ortified at the low concentration must be 75- 125% o f the t rue val ue, an d 85-1 15% wh en fort ified at the mediu m and h igh

concen trations. If th e LF B reco very for an a naly sis batch

does not me et these recovery criteria, the data are considere d invalid, and the source of the problem must be identified and resolved before continuing with ana lyses.

LFB Fortified Concentration Range LFB Recovery Limits
MRL to 2x MRL 75 - 125 % 2 x MRL to highest calibration level 85 - 115 %

9.7 SURROGATE

RECOVERY –

The surr ogate s tandard

is fortif ied into a ll samples , blanks, CCC s, QDCSs, L RBs, and LFSM s and L

FSMDs pri or to ana

lys is. It is326.0-22 also adde d to the ca

libration curve a nd calibr ation che ck standa

rds. The surrog ate is a means of assessing chromatogra phic method performance.

9.7.1 Surrogate recoveries must fall betwe en 90-115% for proper instrument performance and analy

st technique to be verified. The recovery range for the surrogate is extended to 115% to allow for the potential contribution of tr ac e l ev el s o f d ic hl or oa ce ta te as a h al og en at ed or ga ni c d is in fe ct io n b yproduct ( DBP) of d

ichloroa cetic a cid (DCAA

). Backgroun

d levels o f this organic DBP are ra

rely observe d above 50 : g/L (0.05 mg/L ) which constitutes only 5% of the 1.00 mg /L recommended fortified concentration.

9.7.2 When surrogate recovery from a sample, blank, or CCC is less than 90% or greater than 115%, che ck (1) calculations to locate possible errors, (2) standard solutions for degradation, (3) contamination, and ( 4) instrument perfor mance. If those ste

ps do not re

veal the cause of the probl em, reanaly ze the sample.

9.7.3 If the reana

lysis meets the surrog ate recovery criteria, report only

data for the reanaly

zed sample.

9.7.4 If the sample rea

nalysis fails the 90-115% surr ogate recovery

criteria, the analy st should check the

calibra tion by re-inje cting th e most rec ently accept able ca libration standar d. If the calibration sta

ndard fa ils the cr iteria of Section 10.3, recalibrate as described in Section 10.2. I f the calibration standard is acceptable, prepara tion and analysis of the sample should be repeat ed provid ed the sa mple is still

within the

holding t ime. I f this sample reanaly sis also fails the recovery criteria, report all data for that sample as suspect due to surrogate rec overy.

9.7.5 If a

laborat ory chooses t o monitor exclusively

for trac e bromat

e using P CR and the UV/VIS absorbanc e detector, suppression of the eluent MUST be used and the surrogate added a nd monitored on the conductivity detec tor and the appropriate QC criteria for the surr ogate as outlined in Section 9.7.1 must b e met.

9.8 LAB ORATORY F ORTIFIED SAMPLE MATRI X (LF SM) – Anal

ysi s of LFSMs

are re quired in

each an aly sis batch

and are used to de

termine t hat the sa mple matrix does

not adver

sely affec t method a

ccurac y. Additional L

FSM requirements, as described in Section 9.8.4, apply when the PCR system is used for low level bromate in waters disinfected with chlorine dioxide. I f the occurrence of targ et analytes in the sa mples is infrequent, or if historical trends are326.0-23 unavailable, a second L

FSM, or LFSMD (Sect. 9.9), must be pre pared, and analy zed from a

duplicat e of the f ield sampl e used to prepare the LFSM to asse ss method precision. Analytica l batches that contain LFSMDs will not require the analysis of a F ield Duplicate (Sect. 9.9). If a variety of

different sample matrices are analy zed regularly , for example, drinking water from groundwater and surface water sources, method performance should be established for each. Over time, LFSM data should be documented for all routine sample sources for the laboratory.

9.8.1 Within eac

h analy sis batch , a minimum o f one fie ld sample i s fortifi ed as a LFSM for every

20 samples processed. The LF SM is prepared by spiking a sample with an appropriate amount of the appropriate Analyte PDS (Sect. 7. 2.1.2). Se lect a sp iking concentra tion at lea st twice the matrix backgro und co ncent ratio n, if k nown. Use hi stori cal dat a or rot ate th rough a range of concentra

tions when selecting a fortify ing concentration. Selecting a duplicate bottle of a sample that has alre ady bee n analyzed aids in the sele ction of a

ppropria te spiking levels.

9.8.2 Calculate the percent recovery (%R) for each analy

te using the equation

where A = measu

red conc entration in the fortified s ample B = measured concentration in the unfor tified sample, and C = fortification concentration.

9.8.3 Analyte re coveries may exhibit a matrix bias. For samples fortified at or above their native concentration, recove ries should range between 75 - 125%. If the acc

uracy of any ana lyte falls outside the desig nated range, and the CCC performance for that analy te is shown to meet the acceptance criteria, the recovery

is judged to be matrix-biased. The result for that analyte in the unfor

tified sample is labeled suspect/matrix to inform the data user that the results are suspect due to matrix effects.

9.8.4 When the PCR method is us ed for low level br omate analy sis on fiel d samples from PWSs which employ chlorine dioxide disinfection and consequently conta

in chlorite, a LFSM must be prepar ed, exclusively for trace bromate, for eac

h of these field sam ples. I nitially, the fie ld sample i s analyzed and c

hlorite, chlorate and bromide levels are deter mined. Then, a second aliquot of field sample is pretreated to remove c hlorite, as326.0-24 describ ed in Sect

ion 11.1.4 , and ana

lyze d to deter

mine nativ e bromat

e 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 asse ss bromate recovery from that matrix. This additional QC is required to rule out matrix effects and to confirm that the laboratory perfor med the chlorite r

emoval ste

p (Sect. 1 1.1.4) a

ppropria tely . This LFSM should be fortified with bromate at conc entrations close to but greater than the level deter mined in the native sample. Recoveries are determined as des cribed a bove (Se ct. 9.8.2 ). Sample s that fai l the L FSM perc ent r ecov ery criteria of 75 - 125 % must

be re porte d as s uspe ct/ma

trix.

9.9 FIELD DUP LICAT E OR LABO RAT ORY FOR TIFIE D S AMP LE MA TR IX DUPLI CATE (FD or LF SMD) – Within each analysis batch, a minimum of one Field Duplicate (FD) or L aboratory Fortified Sample Matrix Duplicate (LFSMD) must be analy

zed. Duplic ates che ck the pr ecision a ssociate d with samp le collection, preservation, storage, and labor atory proc edures. If targ et analytes a re not routinely observed in fie ld samples, a LFSMD should be analy zed rather than a FD.

9.9.1 Calculat

e the re lative pe

rcent di ffere

nce (RPD)

for dupli cate measurements (FD1 and FD2) using the equation

9.9.2 If a L

FSMD is analyzed instead of a Field Duplicate, calculate the relative percent difference (RPD) for duplicate LFSMs (L

FSM and LFSMD) using the equation

9.9.3 RPDs for F Ds and dup licate L FSMs shoul d fall in th e rang e prese nted in the table below for samples fortified at or above their native conc entration. Greater variability

may be obser

ved when LFSMs are

spiked near the MRL.326.0-25 Concentration Range RPD Limits
MRL to 5 x MRL ± 20 % 5 x MRL to highest calibration level ± 10 %

If the accur

acy of a ny analy te falls outside the designated range , and the laboratory pe

rformance for that analy

te is shown to meet the acceptance criteri a in the L

FB, the recove ry for that a naly te is judg ed to be ma

trix biased. The result for that analy te in the unfortified sample is labeled suspect/ matrix to inf

orm the da

ta user that the re sults are suspect d ue to matrix eff ects

9.10 INST RUMENT PERF ORMANCE CHECK – The l ow-leve l CCC Standar d is evaluated in each analy

tical batch in order to confirm proper instrument performance (Sect. 10.3). This analysis confirms the MRL and demonstrates proper chromatographic per formance at the beginning of each analy sis batch. Chromatographic performance is judged by c alculating the Peak Gaussian Factor (PGF), w hich is a me ans to mea sure pea k sy mmetry and monitor reten

tion time drift in th e surrog ate pea

k over time . The PGF , as dete rmined be low, must f

all betwee n 0.80 and

1.15, and the rete ntion time f

or the sur rogate must be at l east 80% of the

initial re tention tim e when th e IC c olumn was new. I f these c riteria are not met, corrective action must be perfor med prior to analyzing

additional samples. Major maintenance such as replacing columns requires repeating the IDC determination (Sect. 9.2).
9.10.1 The PGF is calculated using the equation

where W(1⁄2) is the peak width at half height, and W ( 1 / 10 ) is the pe ak width a t tenth he ight.

NOTE: Valu es fo r W(1⁄2) and W ( 1 / 10 ) for each peak can be a ttained through most data a

cquisition softwar e packa ges.

9.10.2 Small variations in retention time can be anticipated when a new solution of eluen t is prepa red but if sudden sh

ifts of mor

e than 5% are obse rved in the surrogate retention time, some ty pe of instrument problem should be326.0-26 suspecte d. Potentia

l problems

include i mproper ly prepare d eluent, erroneous method parameters such as flow r ate or some other sy stem problem. The chromatographic profile ( elution order) of the target anions following an ion chromatographic ana lysis should closely

resemble the profile displayed in the test c hromatogram that was shipped when the column was purchased. As a column age s, it is normal to see a gradual shift and shortening of retention times, but if after severa l years of use , extensive use over less than a y ear, or use with ha

rsh sample s, this retention time has noticeably shifted to any less than 80% of the original record ed value , the colu

mn requir es clea ning or r eplace ment, esp ecially

if resolution problems are beginning to occur between previously

resolved peaks. A laboratory

should retain a historic record of retention times for the surrogate and all the targ et anions to provide evidence of an analy tical

co lu mn ’s ef

fi ci en cy.

9.10.3 If a

laborat ory chooses t o monitor exclusively

for trac e bromat

e using P CR and the UV/VIS absorbanc e detector, suppression of the eluent MUST be used and the surrogate added a nd monitored on the conductivity detec tor and the appropriate QC criteria for the surr ogate as outlined in Section 9.7.1 must be met.

9.11 QUALI TY CONTROL SAMPLE ( QCS) – Each time new Calibration Standards (Sect. 7.2.3) are prepared, or a t least quarterly, a

nalyze a QCS from a sourc e different from the source of the ca libration standards. The acceptance cr iteria for the QCS is 85-115% of the true value. If measured analy

te concentrations are not of acceptable accura

cy, che ck the entire analy tical procedure to locate and corre ct the problem source.

10. CALIBRATI ON AND STAN DARDIZ ATION

10.1 Demonstration of acceptable initial calibration is required prior to pe rforming the IDC a nd befor e any samples a

re anal yze d. It i s also re quired in termitten tly throughout sample analy sis to meet required QC performance criter ia summarized in Tables 4 and 5. I

nitial ca libration verific ation is pe

rformed using a Q CS (Sect. 9.11) as well as with each analy sis batch using Continuing Calibration Check Standard s. The pr

ocedure for esta blishing the initia l calibra tion curv e is described in Section 10.2. The procedure to verify the calibration with each analysis batch is desc

ribed in Section 10.3.

10.2 INI TIAL

CALI BRATION

10.2.1 Establish ion chromatographic configura tion and operating parameters equivalent to those indicated in Table 1 and Figure 1.326.0-27 10.2.2 Estimate t

he calibration ra

nge ove r which the instrume

nt respon se is linear. On the conductivity de tector for the four target a nalytes (chlorite, bromate, bromide and chlorate) the linear ra nge should cover the expected concentration range of the f ield samples and should not extend over more than two orders of magnitude in concentration. The method development data we re colle cted on si

ngle linear ca

libration s that spa

nned 5 to 5 00 ug/L for chlorite, bromide and chlorate and 5 to 100 ug/L bromate for the conductivity detector a

nd 0.5 to 15.0 ug/L for bromate on the absorbance detector.

10.2.2.1 If quantification is desired over a larger rang e, then two or more separate calibration curves must be prepa red.

10.2.2.2 A minimum of five Calibration Standards (Sect. 7.2.3) should be prepar ed for e ach cal ibration. It is r ecommen ded that a t least four of the Calibration Standards are at a conce ntration $ the MRL. B ecause

high co ncentra

tions of chlorite c an inter fere wi th the postcolumn analysis of low levels of br omate, the conductivity and absorba

nce detectors must be calibrated separately

.
10.2.2.3 When quantitated using the initial calibration curve, each calibra tion point, except the

lowest poi

nt, for e ach ana

lyte should calculate to be 85-115% of its true value. The lowest point should calculate to be 75-125% of its true value. Failure to mee t this criteria may indica

te future difficulty

in meeting CCC QC requirements during the analy sis batch.

10.2.2.4 Since the concentration ranges in ac tual field samples by conductivity detection for chlorite, bromide and chlorate are expected to cover two orders of magnitude, the use of calibration standards in the range 5 - 500 : g/L is recommended.

10.2.2.5 Bro mat e co nce nt rat io ns a re e xp ect ed t o be si gni fic ant ly lo wer . It is su ggested that t he con ducti vity det ector b e cali brated usin g bromate calibration standard levels in the rang e 5 - 100 : g/L. Add it io nal ly, r epo rt v alu es f or b rom ate by co ndu cti vi ty ON LY when they a

re measured by

the PCR above 15.0 ug/L. The conductivity detector ma

y exhibit a response for broma te at concentrations below 15.0 ug/L , but these should not be reported. When usin g both detect ors, P CR res ults for bro mate i n thi s range (5 - 15 ug/L) will have

far better precision and accur acy.326.0-28 10.2.3 Prepare a set of at least 5 calibration standar ds as described in Section 7.2.3. The lowest concentration calibration standard must be at or be low the MRL, which may

depend on system sensitivity

.
10.2.4 Inject 225 : L of each ca libration standard and tabulate peak area response s against the concentration for the four target analy

tes, the surrogate from the conductivity detector, and bromate from the postcolumn absorbance detector. Prepare calibration curve s using linear regression analy sis for each analy

te on the conductivity detec tor and using a quadratic poly nomial function for bromate on the absorbance dete ctor.

10.2.4.1 Use of peak areas are strong ly recommende d 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 compe te for exch ange si tes le ading t o peak broad ening. However, poorly

drawn baselines can have a more significant influence on peak areas than pea k heights. It is the analy

st’s responsi bility to revie w all chr omatogr ams to ens

ure acc urate baseline integr ation of ta

rget a naly te peaks

.
10.2.5 After establishing (or re-establishing ) calibration curves, the accurac y of this calibration must be verified through the analy sis of a QCS or an externally prepar

ed second source standard. The QCS should be prepar ed at a conc entration near th e middle o f the ca libration range . As spec ified in Section 9.11, determined concentrations must fall within ± 15% of the stated va lues.

10.3 CONTINUI

NG CALI

BRATION CHECK (CCC) – I nitial calibrations may be stable for extended periods of time. Once the calibration curve s have been established for both the conductivity a nd absorbance detectors, they must be verified for each analy

sis batch prior to conducting any field sample analy ses using CCCs . The fir st CCC each day must be at or below the MRL i n order t o verify instrument sensitivity prior to any ana

lyses. Subsequent CCCs must be run after every

10 field samples and should alternate between a mid- and hig h-level CCC. LRBs, CCCs, LFSMs and L FSMDs are not counted as field samples.

10.3.1 A low-le

vel CCC must be de

termined to be vali d each d

ay prior to analy zing any samples b y in

jecting an aliquo t of the a

ppropria te CCC under the same instrumental conditions used to collect the initial calibra tion. Since

two detec

tors are incorpor ated in th is method, this must be accomplished by

using a mixed calibration check standard for the four conductivity analy

tes and a separate low-level bromate CCC for the326.0-29 absorbance detector. The low-level CCC for both detectors must be at or below the MRL. Percent rec overy for the low-level CCC must be in the range of 75 - 125% before the analyst is allowed to ana lyze samples.

10.3.2 Additiona

l CCC standa

rds must be

analy zed afte r every tenth fie ld sample and at the end of the analysis batch. If more than 10 field samples a re included in an analy sis batch, the analyst should alterna te between the mid- and high-level CCC Standards. Percent recovery for the mid- and high-level CCCs must be in the range of 85 - 115%.

10.3.3 If the calibration ver ification criteria listed above are not met, or the retention times shift more than ± 2% from the last acceptable initial or continuing calibration check standard for a ny analy te, then all samples analyzed afte

r the last acceptable calibration chec k standard are considered invalid and must be reanaly zed. The source of the problem must be identifie d and res olved bef ore rea naly zing the s amples or

continuin

g with the analyses.

10.3.2.1 In the case whe

re the end calibration failed to meet perfor mance criteria, but the initial and middle calibration check standards

were a ccepta ble, the s amples br

ackete d by

the acc eptable calibra tion chec k standar ds may be repor ted. Howe

ver, all field samples between the middle and end calibration check sta ndards must be reanaly

zed.

11. PROCEDURE

11.1 SAMPLE PREPARATION

11.1.1 For refrigerate d or field samples arriving at the laboratory cold, ensure the samples h ave come

to room tem

peratur e prior to conducti ng sampl e analysis by

allowing the samples to warm on the bench for at lea st 1 hour.

11.1.2 Prepare

a 10.0-mL

aliquot of

surrog ate for

tified sa mple which can be

held for direct manual injection or used to fill an autosampler vial. This is done by adding 20 : L of t

he surro gate so lution (Se ct. 7.2.2 ) to a 20- mL disposabl e plastic

micro be aker. N ext, place a 10.0-mL

aliquot of

sample in the micro beaker and mix. These volumes may be adjusted to meet specific laboratory

autosampler volume requirements provided the fortified surrogate concentra tion is at the prescribed concentration of 1.0 mg/L . The samp le is now r eady for ana lys is.326.0-30 NOTE : The less than 1% dilution error introduced by the addition of the surrogate is considered insignifica nt. If a laboratory

chooses to monitor exclusively for trace

bromate using PCR and the UV/VIS absorba nce detector, suppression of the eluent MUST be used and the surrog ate added and monitored on the

conducti vity detector and the

appropr iate QC criteria for the s urroga te as outli ned in Section 9.7.1 m

ust be met.

11.1.3 Using a Luer loc

k, plastic 10

- mL sy

ringe, withdraw the sample from the micro beaker and attach a 0.45

- : m particulate filter (demonstrated to be free of ionic con taminants ) direc tly t

o the sy ringe. Filter the sample

into an autosampler vial (if vial is not designed to automatically filter) or manually load the i njection loop injecting a f

ixed amount

of filter ed, well mixed sample. If using a manually loaded injection loop, flush the loop thoroughly be

tween sample analy sis using sufficient volumes of each new sample matrix.

11.1.4 CHLORI

NE DIOXI

DE - TREATED WATERS CONTAINI NG CHLO RITE

– Treatment plant s that use chlorine dioxide as p art of the ir treatment process can produce hig h levels of chlorite in samples. Since chlorite can interfere with the postcolumn quantitation of low levels of bromate as descr ibed in Sec

tion 4.6, c hlorite mu st be removed from these samples prior to an

aly sis. (11) The oxidation-reduction reaction between ferrou s iron and

chlorite (12) is used to r

emove ch lorite wit hout any adverse affects on the bromate concentration

. (13)

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 (Sec t. 7.1.7). After mixing, verify the pH is between 5 and 6 using pH test strips, add 40 uL of ferrous iron solution (Sect. 7.1.6), mix and allow to react for 10 minutes. Filter the reaction mixture using a 0.45 micron particulate filter (Sect. 6.10) attached to a 10-mL syringe into the barrel of a second syringe to which a pre-conditioned hy drogen cartridge ( Sect. 6.11) is attached. Pass the solution through a hy droge n cartr idge at a flow rat e of appr oximately 2 mL pe r minute. D iscard the first 3 mL, and collect an appropr iate volume (depending on autosampler vial size)for ana

lys is. Add the

respec tive volume

of surro gate solution, depending on the volume collected. The sample is ready for analy sis (Sect. 11.2).

NOTE: Pretreated samples can be held for no more tha n 30 hours after initial pretreatment. I f this time has expired, the pretreatment steps must b e repea

ted on a se cond aliq

uot of both

the field sample matrix and t

he respe ctive L

FSM.326.0-31 11.1.4.2 In order to ensure da ta quality, all samples from PWSs which utilize chlorine dioxide which have been pretreated to remove chl ori te, MUS T al so b e us ed t o pr epa re a pre tre ate d LF S M specif ic to trace bromate. This LF SM 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 a nd chlorite, chlorate and bromide levels are determined. T hen, a second aliquot of field sample is pretreated to remove chlorite, as describ ed above

and ana lyze d to deter

mine nativ e bromat

e concentrations. A third aliquot of the field sample then must be fortified with bromate, pretreated to remove chlor ite, and analyzed to assess bromate recovery from that matrix. This additional QC is required to rule out matrix effects and to confirm that the lab ora to ry pe rfo rme d t he c hl ori te r emo val st ep a ppr opr iat ely. If the bromate recovery

falls outside the acceptance rang e of 75 - 125% (Sect. 9.8), that particular sample should be reported a s suspe ct/ma

trix.

11.1.4.3 All samples from PWSs that utilize chlorine dioxide, which have been pretreated to remove chlorite, MUST also include a n additional pretreated LRB in the analytical ba tch (Sect. 9.4.2).

11.1.4.4 Suppressor devices which have had long ter m 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 f

or fluoride or phosphate, the suppressor should be cleane d accor

ding to th e manufa

cturer ’s reco mmendations.

11.2 SA MP LE AN ALYS IS

11.2.1 Table 1 summarizes the recommended operating c onditions for the ion chromatograph and deliv ery of the pos tcolumn re agent. Inc luded in th is table are the actual retention times and Detection Limits that were determined during the development of this method. Other columns or chromatographic conditions may be used if the requirements of Section 9 are met.

11.2.2 Establish

a valid in itial cal ibration a s descri

bed in Section 10.2 a

nd comple

te the IDC (Sect. 9.2). Check sy stem calibration by ana

lyzing a low-leve l CCC (Sect. 1 0.3.1) a s part of the initia l QC for the

analy sis batch and, if required, recalibrate as desc ribed in Section 10.2.326.0-32 11.2.3 Inject 225 : L of each sample. Use the same size loop for standards and samples. An automated constant volume injection sy stem may also be used.

11.2.4 The width

of the re tention tim e window u sed to mak e identif ications should be based upon measurements of actual rete ntion time variations of standards

me as ur ed ov er se ve ra l d ays . Three times the standard deviation of retention time can be used to calculate a sugg ested window size for each analy te. However, the experience of the analy st should weigh heavily

in the interpretation of chromatograms.

11.2.5 If th e respon se of a sa mple ana lyte exceeds t he calibration ra

nge, th e sample must be diluted with an appropriate amount of EDA fortified rea gent water and reanaly

zed.

11.2.6 Should more complete resolution be needed between any two coeluting peaks, the eluent (Sect. 7.1.2) can be diluted. This will extend the run, however, and will cause late eluting anions to be r etained even longer. The analyst must verify

that this dilution does not negatively aff ect performance by repea ting the IDC (Sect. 9.2), a nd by reesta

blishing a valid initial calibration curve (Sect. 10.2). As a specific pr ecaution, upon dilution of the carbonate eluent, a peak for bica rbonate may be

observed on the conductivity detector w

ithin the retention time window for bromate which will neg atively

impact the

analy sis.

11.2.6.1 Eluent dil

ution will r

educe the overa

ll respon se of an a

nion due to chromatographic band broadening which will be evident by shortened and broadened peaks. This will adverse ly effe ct the Detecti on Lim

it for each analy

te.

11.3 AUTOMATED ANALYSI S WITH METHOD 326.0

11.3.1 Laboratories conducting analy ses on large numbers of samples often pre pare large analysis batches that are run in an automated manner. When conducti ng auto mated analy ses, car eful atte ntion must be

paid to al l reservoirs to be certain sufficient volumes are available to sustain extended operation. Laboratorie s must ensure that all QC performance criteria a re met as de scribed

in prece ding sec

tions to en sure the ir data a re of ac ceptabl e qu al it y. 11.3.1.1 Special attention must be paid when the PCR reservoir is refilled. The PCR is sta

ble for only

24 hours a

nd conse quently

the rese rvoir must be re gularl

y f illed with f

reshly prepar ed reag ent. Since

this is a pneumatically dr

iven system, the baseline will re quire a326.0-33 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 sequenc es must be carefully constructed to meet required QC specifications and frequency (Sect. 17, Table 5). To help with this task, an acceptable sequence for a sample analysis batch, with all the methodrequired QC, is shown in Table 6. This schedule is included only as an example of a hypothetical a nalysis batch wher

e the analy st desires to collect data using both detectors. Within the analy sis batch, references to exact concentrations for the CCCs are for illustrative purposes only . The analyse s for samp le #14 provides an e xample of the QC requ

irements for a co mplete cond uctiv ity and t race broma te PCR anal ys is of a sampl e from a PWS employing c

hlorine dioxide disinfection.

12. DATA ANALYSIS AND CALCULATIONS

12.1 Identify

the method analytes in the sa mple chromatogram by

comparing the retention time of th e suspected anal yte peak to th e reten

tion time of

a known a

naly te peak in a calibra tion stand ard. I f analy

te reten tion times h ave shif

ted (ge nerally towards shorter times) since the initial calibration, but are still within acceptance criteria and are reproducible dur ing the analy sis batch, the analyst should use the retention time in the daily calibra tions to confirm the presence or absence of ta rget analy tes.

12.2 Compute sa

mple conc entration using the initial c alibrati on curve gener ated in Section 10.2.

12.3 Report ONLY those values that fa ll between the MRL and the highe st calibration standard. Samples with target analy te responses exceeding the highest standar d must be diluted and reanaly zed. When this is not possible the alternate calibration procedures described in Section 11.2.5 must be followed.

12.3.1 Report bromate concentrations using the postcolumn UV/Vis absorbanc e detector when th ey

fall betw een the M

RL and 15.0 ug

/L. Whe n bromate concentrations exceed 15.0 ug/L , as detected by UV/Vis absorbance, either report by c onductivity, calibrate the postc olumn UV/Vis absorbance detector to a higher bromate concentration, or dilute the sa mple.

12.4 Report analyte c oncentrations in : g/L (usually with two significant figures).

12.5 Software

filterin g of the postcolum

n UV/Vis a

bsorbanc e signa

l is recom mended to improve the precision of peak measurements, minimize non-random noise and326.0-34 improve peak appearance, e nsuring that all QC requirements for the method are met. Olympic smoothing (25 points, 5 seconds with 1 itera tion) was chosen using peak area for quantitation because it was determined to have minimal effect on peak height and/or area

. (14) The use o f alternate smooth ing rout ines is ac ceptabl e providing all QC criteria are met.

13. METHOD PERFORMANCE

13.1 Table 1 lists the standard conditions, typical re tention times and single laboratory Detection Limits in reage nt water, as determined for each of the inorganic oxyha

lide DBPs and bromide.

13.2 Table 2 sh

ows the pr

ecision a nd accu racy of the tra ce broma te measu rement, evaluated on both detectors, at two fortified concentr ations, in reagent water (RW), a simu late d hig h ioni c str

eng th wa ter (HIW) and

a simu late d hig h org anic (HOW) content water. The mean recover ed bromate concentration (accur acy re lative to the fortified level) and the precision (expressed as %RSD of the re plicate analy ses) are tabulated. The HIW was desig ned to simulate a high ionic strength field sample and th e HO W d esi gne d t o si mu lat e a h igh org ani c co nt ent fie ld sam pl e. T he H IW was prepared from reag ent water which was fortified with the common anions of chloride at 100 mg/L, ca

rbonate at 100 mg/L, nitrate at 10.0 mg/L as nitroge

n, pho sph ate at 1 0.0 mg/ L as p hos pho rou s, a nd s ul fat e at 100 mg/ L. (1) The HOW was prepar ed from r eage nt water fortifie d with 1.0 mg

/L humic acid. (1)

13.3 Table 3 summarizes the single laboratory accuracy (%Recovery

) and precision (% RSD) for each anion included in the method in a variety of waters for the standard conditions identified in Table 1.

14. POLLUTION

PREVENT ION

14.1 For information about pollution prevention that may be applicable to laboratories and research institutions, consult "Le ss is Better: Laboratory Chemical Management for Waste Reduction," available from the America n 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 ana

lyti cal proc edures d

escribe d in this met

hod generate r

elativel y small amounts of waste since only small amounts of reagents are used. The ma trices of concern are finished drinking wa ter. However, the Agenc y require s that laboratory waste management practice s be conducted consistent with all applicable rules and regulations, and that laboratories protect the a ir, water, and land by

minimizing and326.0-35 controlli ng all r elease s from fume hoods a nd bench operati ons. Also, compliance is required with any

sewage discharge

permits and regulations, particularly the hazardous waste identification rules and land disposal restrictions. For furthe r information on waste management, consult “The Waste Mana gement Manual for Laboratory

Personnel” also available from the American Chemica l Society at the address in Section 14.1.

16. REFEREN CES

1. U.S. EPA Method 300.1. “Determination of Inorg anic Anions in Drinking Water by Ion Chromatography

”. EPA Document number: EPA/600/R-98/118. NTIS number PB98- 16919 6 INZ.

2. Glaser, J.A., D.L. Foerst, G.D. McK ee, S.A. Quave, and W.L. B udde, "Trace Analyses for Wastew aters," Environ

. Sci

. Technol . 1981, 15, 1426-1435.

3. Wagner, H..P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “US Environmental Protection Agenc

y Me thod 326.0 , a New Me

thod for M onitoring

Inor ganic Oxyhalides and Optimization of the Postcolumn Derivatization for the Selective Determination of Trace L evels of Bromate.” J. Chro

. A , 2002, 956, 93-101.

4. “OSHA Safety a

nd Health Standards, General I ndustry,” (29CFR1910). Occupational Safety

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

5. ASTM Annual Book of Standards, Part II , Volume 11.01, D3370-82, “Standard Practic e for Sam

pling Wat

er,” Ame rican Soc iety

for Test ing and Materia ls, Philadelphia, PA, 1986.

6. “Carcinogens-Working with Carcinog ens,” Publication No. 77-206, Department of Health, E ducation , and Welf are, Pub lic Heal

th Servic e, Cente

r for Dis ease Con

trol, National Insti tute of Oc cupational Safet y a nd Health , Atlanta , Georgia, Aug ust 1977.

7. “Safety I

n Academic Chemistry L aboratories,” 3 rd Edition, American Chemical Society Publication, Committee on Chemical Safety, Washington, D.C., 1979.

8. Wagner, H..P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “I mproving the Performance of EPA Method 300.1 for Drinking Water Compliance Monitoring.” J. Chrom. A. Special Edition of the 2002 International Ion Chromatography Smyposium (in press).326.0-36

9. Standard Methods for the Examination of Water and Wastewater, “Method 4500- ClO 2 ,C Amperometric Method I (for the determination of Chlorine Dioxide),” 19 th Edition of Standard Methods (1995).

10. Hautman, D.P. & Boly ard, M. “Analy sis of Oxyhalide Disinfection By -products and other Anions of Interest in Drinking Water by Ion Chromatography .” J. Chrom

. A , 1992, 602, 65-74.

11. Wagner, H..P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “Analy sis of 500 ppt Levels of Bromate

in Drinking Waters Using Direct I njection Suppressed Ion Chromatography

with a Single, Pneumatically D elivered Postcolumn Reagent.”J. Chrom

. A , 1999, 850, 119-129.

12. Iatrou, A. and Knocke , W.R. “Removing Chlorite by the Addition of Fer rous Iron”. Journ al of

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

13. Wagner, H..P., Pepich, B.V., Hautman, D.P. and Munch, D.J. “Eliminating the Chlorite I nterfe rence i n US Environmental Pr

otection Agenc y Me thod 317.0

Permits the Analysis of Tra

ce Bromate L evels in all Drinking Water Matrices.” J. Chrom.

. A , 2000, 882, 309-319.

14. Schibler, J.A., “ Improving Precicion and Accuracy with Software-based Signal Filtering”. American Labora tory , (December, 1997), 63-64.326.0-37

17. TABLES, DIAG

RAMS, F LOWCHARTS A ND VALIDA TION DATA

TABLE 1. CHROMATOGRAPHIC COND ITIONS AND ME THOD DETECTI ON LIMITS IN

REAG ENT WATER FOR

THE IN ORGAN IC OXYHA LIDE D ISINFEC TION BYPRODUCTS AND BROMIDE.

Standard Co nditions and Equipm ent (a) : Ion Chromatograph: Dionex DX500 Sample Loop: 225 : L Eluent: 9.0 mM Na 2 CO 3 Eluent Flow: 1.3 mL /min Columns : Dionex AG9 -HC / AS9-H C, 4 mm Typ ical Sy

stem Bac kpressur e: 2300 psi Conductivity Suppressor: ASRS-1, exte rnal wat er mode, 100 mA cur

rent for conducti vity PCR Suppressor: ASRS-1 use d with sulf uric ac id rege

nrant to a cidify the PCR Detectors: Dionex CD20 suppressed conductivity detector , background conductivity: 24 : S Dionex AD20 Absorbance Detector, 10 mm cell path length, se t at 352 nm (deuterium lamp) Postcolumn Reagent Flow: 0.4 mL/min Postcolumn

Reactor Coil: knitted, p otted for heater , 500 uL

interna l volume Postcolumn Heater: 80 ° C Postcolumn Regenerant 150 mN H 2 SO 4 , 2.5 mL/min, effluent pH < 2 Total analysis time: 25 minutes
Analyte R

etentio n Times a nd Detection Limi ts :

Analyt e Retention Time (b)

(min.) Fortified

Conc. ( : g/L) # of

Reps. Detection

Limit ( : g/L)
Chlori te 4.11 5.0 8 2.0 Bromate (c) Bromate ( d) 4.73 5.28 5.0

0.50 8

8 1.2

0.17 Surrogate: DCA 8.01

Bromide 9.18 5.0 8 1.7

Chlora te 10.07 5.0 8 1.7 (a) Ment ion of t rade na mes or com

merci al produ

cts does not con stitute e

ndorsem ent or
recommen

dation for use. (b) Refer to chrom

atograms in Figures 2 and 3

. (c) Bromate by

conductivity detection (d) Bromate by absorbance detectio n326.0-38

TABLE 2. SINGLE LABO RATORY P RECISION IN VARIOUS M

ATRICES F OR BROMATE BY ABSORBANCE DETECTION.

PRECISIO N

Matrix Detection Fortified Conc. ( : g/L) # of Reps. Mean ( : g/L) %

RSD Reage nt Water Absorbance 1.0 8 1.1 4.4

Absorbance 5.0 8 5.2 2.1 High I onic Water Absorbance 1.0 8 1.1 4.2

Absorbance 5.0 8 5.2 2.0

High Organ ic Water Absorbance 1.0 7 1.1 3.4

Absorbance 5.0 8 5.2 3.2

Standard Conditions: Same as listed in Table 1.326.0-39

TABLE 3. SINGLE-LA BORATORY PRECISION A ND RECOVE RY FOR T HE INORGANIC DISINFECTION BY-PRODUCTS, BROMIDE AND SURROGA TE.

Analyt e Matrix Fortified Conc. (ug/L) # of

Replicates Mean

% Recovery %RSD
Chlorit e RW 100 500 8

8 107

108 3.0

1.2

HIW 100

500 8

8 102

106 2.0

0.71
HOW 100

500 8

8 99.3

107 2.7

0.49
Bromate by Conduc tivity RW 10.0 25.0 8

8 102

99.8 4.6

4.3

HIW 10.0

25.0 8

8 103

92.9 3.8

11
HOW 10.0

25.0 8

8 101

97.6 8.1

5.9

Bromide RW 10.0 25.0 8

8 97.5

104 5.3

5.1

HIW 10.0

25.0 8

8 108

104 4.8

5.0
HOW 10.0

25.0 8

8 104

99.7 6.1

3.7

Chlorat e RW 100

500 8

8 111

104 1.7

0.97

HIW 100

500 8

8 99.0

100 2.3

0.66
HOW 100

500 8

8 101

105 2.8

1.1
Surrog ate RW 1.00 8 8 108

106 6.1

4.7

HIW 1.00 8 8 103

105 1.3

2.1
HOW 1.00 8 8 108

108 4.4

4.0
RW = Reagent Water; HIW = Hig h Ionic Strength Water; HOW = Hig h Organic Water326.0-40

TABLE 4. INITIAL DEM ONSTRATION OF CAP ABILITY QC R

EQUIREMEN TS

.

Reference Requirement Specification and Frequency Accept ance C riteria
Sect. 9.2.1 and 9.4 Initial

Demonstration of Low System Background Analyze a method blank (LRB) and determ ine that all targ et analy

tes are below 1⁄2 of the p roposed MRL pr ior to performing the IDC The LRB concentration must be

# 1/3 of the proposed MRL
Sect. 9.2.2 Initial

Demonstration of Accuracy (IDA) Run mid- level QCS and determine

recover y. Conductivity: analyze 7 repli cate LFBs

recommen

d fortify at 20 ug

/L Absorbance: ana lyze 7 replicate LFBs

recommen

d fortify with brom

ate at 2.0 ug/L Calculate average rec overy of IDA replicates QCS recovery must be ± 15% of true value.
Mean % recovery for IDA replicates must be ± 15% of true value.

Sect. 9.2.3 Initial

Demonstration of Precision (IDP) Calculate the %RSD of the IDA

replicates. %RSD must be # 20%

Sect. 9.2.6 Detecti on Lim it Determination Select a fortifying level at 3- 5 times the estimated instrum

ent detection limit at or lower than the MRL. Analyze 7 replicate LFBs Calculate over at least 3 days using equation in Section 9.2 .6 - do not subtract blank Detection Limit must be < 1/3 the MRL326.0-41

TABLE 5. QUA

LITY CO NTROL

REQUI REMEN TS (SU MMARY)

.

Reference Requirement Specification and Frequency Accept ance C riteria
Sect. 8.3 Sample Holding

Time / Preservation Bromate 2 8 days, refrig . at <6 o C / EDA P

reservation Bromide 28 days, ED A Permitted Chlorate 28 days, refrig . at <6 o C /

EDA Preservation Chlorit e 14 days, refrig . at <6 o C / EDA Preservation Holding tim e and temperature m

ust not be exceede d. ED A adde d to all samples

Sect. 9.4 Laborat

ory Reagent Blank (LRB) Incl

ude LR B with every

analy sis batch (up to 20 sam

ples) Analy ze pri or to analyz ing fi eld samples All analytes m ust be

# 1/3 MRL

Sect. 9.4.2 (specifi c to PCR) PRETREATED

Laborat ory Reagent Blank REQUIR ED in any an

alysis batch which i nclud es sampl es whic h have been pr etreated to rem ove ch lorite prior to PCR m

easurement of trac e bromate. PCR measure d bromate < 1/3 MRL

Sect. 9.6 Laborat

ory Fortified Blank (LFB) Laborat ory m ust anal yze LFB in each analysis batch following the first CC C. Ca

lculate %REC p rior to analyzing samples LFB re cover y fort ified at:

$ MRL to 5X MRL = 7 5 - 1 25%

$ 5X MRL to highest CCC = 85 - 115% Sample results from

batches that fail LFB a re inv alid

Sect. 10.2 Initial

Calibration Conductivity: generate calibration

curve using at least 5 standards Absorbance: generate

calibration

curve using at least 5 brom ate standards The lowest calibration standard MUST be at or below the MRL 4 CAL standards sh

ould be above the MRL

Sect. 9.5 and Sec t. 10.3 Continuing

Calibration Check (CCC) Verify initial calibration by

analy zing a low l evel C CC prio

r to analyzing samples. C CCs are then injected after every 10 samples and after the last sample, rotating concentrations to cov er the calibrated range of the instrument. Recov ery fo r each a nalyte must be 85- 115% of the true value for all but the lowest level of calibration. The lowest calibr ation level CCC must be 75- 125% of the true value All acceptable data MUST be bracketed by valid CCCs326.0-42

TABLE 5. QUALITY CONTROL REQUIREM ENTS (SUMMARY CONTINUED)

.

Reference Requirement Specification and Frequency Accept ance C riteria
Sect. 9.7 Surrog ate Dichloroacetate is added to all blanks, samples and stand

ards Surrogate recov ery must be 90 - 115%. Samp les that

fail surrogate recove

ry must be reanalyzed. If second analy sis fails

label re sult as suspect/matrix

Sect. 9.8

Sect. 11.1.4.3 Laborat

ory Fortified Samp le Matrix (LFSM) Must add known amount of each target

analy te to a m inimu m of 5 % of field samples or at least one within each analysis batch for bo th detectors LFSM must be fortified above the native level and

at no greater than 5 x the highest field sam

ple concentration Calculate target analy

te recovery us ing formula (Sect. 9. 8.2) When field samples from chlorine dioxide plants which c ontain c

hlorite are pretreat ed prior to the PCR

measureme

nt of trace bromate, an additional LFSM m

ust be prepared for each pr etreated field sa mple (Sect. 9.8.4) Recovery sh ould be 75 - 125%

If fortified s ample

fails the recovery c

riteria, label both as suspect/matrix.

Sect. 9.9 Field Duplicate

(FD)

or Laborat ory Fortified Samp le Matrix Duplica te (LFSMD) Analy ze either a FDor LFS MD for a minimum of 5% of field sam

ples or at least one within each an

alysis batch for both detectors.
Calculate the relative p ercent difference (RPD) using form

ula in Section 9.9.1 The RPD for concentrati ons at MRL to 5 x MRL should be ± 20% on both detectors, and ± 1 0% on bo th detectors for concentrations at 5 x MRL t o high est CCCs. If this range is exceede d, label both as suspect/matrix

Sect. 9.10 Instrume

nt Performance Check (IPC) Calculate Peak G aussian Factor (PGF)

using equation (Sect. 9.10.1) and monit or reten tion tim e for su rrogat e in the initial CCC each d

ay PGF must fall between

0.80 and 1.15 Ret. Time (RT) for surrog ate m

ust rem ain 80% of initial RT when column was n

ew326.0-43

TABLE 6. EXAMPL E SAMPL E ANA LYSIS BA TCH WIT H QUALI TY CONT ROL REQUIREMENTS

Injection # Sample Description Acceptance Criteria

1 Laboratory reagent bl ank (LRB) # 1/3 MRL

2 ICCS con

ductivity detector (5.0 μg/L) 3.75 to 6.25 μ g/L

3 ICCS abs orbance detector (0.5 μg /L) 0.375 to 0.62 5 μg/L

4 Labo rat ory Fo rti fie d Bla nk (LF B) - conductivity de

tector ± 25 % fortified level

5 LFB - ab sorbance detector ± 25 % fortified level

6 Field sample 1

7 Field sa

mple 1 - Laborat

ory Duplicate

(LD) (a) ± 15 % RPD

8 Field sample 2

9 Field sa

mple 2 - L aborato ry Fo rtified S ample Matrix (LFSM) (a) at conc entrations spec ific for conduc tivity detecto r ± 25% fortified level

10 Field sample 2 - LFSM spe cific 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 conductiv ity detector (75.0 μ g/L) 63.8 to 86.3 μ g/L

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

21 Field sample 11326.0-44

22 Field sample 12

23 Field sample 13

24 Field sample 14 - (finished wa ter from PWS usin

g chlorine dioxide)

25 Pretreat

e (Sect. 9.3.1 .2) usi

ng the acid/Fe (II

) chlori te removal pro cedure (Sect. 11.1.4 ) # 1/3 MRL

26 Field sample 14 (b) - (finished water from PWS usin g chlorine dioxide) pretreated w ith acid/Fe(II

) (Sect. 11.1.4)

27 Field sample 14 - (finished wa ter from PWS usin

g chlorine dioxide) LFSM specific for trace bromate on the absorba nce detector, p

retreate d with acid/Fe (II

) (Sect. 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 conductiv ity detector (500.0 μg/L) 425 to 575 μg /L

34 ECCS absorbance d etector (15.0 μg/L) 12.8 to 17.3 μ g/L

(a) If no analy

tes are observed ab ove the MRL for a sample, an alternate sample wh ich contains reportable values shou

ld be selected as the labo ratory duplicate. A

lternately, the LFS M can be selected and reanalyz ed as the laboratory matrix duplicate ensu ring the collection of QC data for precision.

(b) Field sa

mple #19 wa s the fin

al field sampl e perm

itted in this ba tch but 20 total

field sa mples were analyzed. Field sa mple #14 wa s analy

zed both initia

lly and as a a

cid/Fe ( II ) pretre ated sam ple, therefore, it account ed for t wo “fie ld sam

ple ana lyses” toward the m aximu m of t wenty in an a nalysi s batch (Sect. 3.1).326.0-45

Figure 1: Schematic detailing the configuration of postcolumn har dware addition to an ion chromat ograph. Mention

of trade names or commerc ial produ

cts does n ot constitu

te endorsement or recommendation for use. I f the requirements found in Section 9 are met, equivalent products or hardware can be employed.

NOTE: I n a ty pical Method 300.1 hardwa re conf igurat ion, a bac kpressur e coil is included after the conductivity

cell as p art of the

waste str eam whe n this manufacture’s equipment is used. These backpre ssure coils are not required when the Method 326.0 instrument configuration is employ ed since the additional PCR system components, placed in-line, function in the same capacity and provide sufficient backpressure.326.0-46

Figure 2: Reaent w ater fo rtified w ith bromat

e at 10 ug /L on b oth detectors.326.0-47 .

Figure 3: Reagent water fortified with inorg anic oxyhalide disinfection by -products and bromide a

t 20.0 ug /L an d bromate at 10 ug /L on b oth detectors.