1、Designation: D 6581 00 (Reapproved 2005)Standard Test Method forBromate, Bromide, Chlorate, and Chlorite in Drinking Waterby Chemically Suppressed Ion Chromatography1This standard is issued under the fixed designation D 6581; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of D
3、efense.1. Scope1.1 This test method covers the determination of the oxy-halides - chlorite, bromate, and chlorate, and bromide, in rawwater, finished drinking water and bottled (non-carbonated)water by chemically suppressed ion chromatography. Theranges tested using this method for each analyte were
4、 asfollows:Chlorite 20 to 500 g/LBromate 5 to 30 g/LBromide 20 to 200 g/LChlorate 20 to 500 g/LThe upper limits may be extended by appropriate sampledilution or by the use of a smaller injection volume. Other ionsof interest, such as fluoride, chloride, nitrite, nitrate, phosphate,and sulfate may al
5、so be determined using this method. How-ever, analysis of these ions is not the object of this test method.1.2 It is the users responsibility to ensure the validity ofthese test methods for waters of untested matrices.1.3 This test method is technically equivalent with Part B ofU.S. EPA Method 300.1
6、2, titled “The Determination of Inor-ganic Anions in Drinking Water by Ion Chromatography”.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practi
7、ces and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Standard Practice for Determination of Precisionand Bias of Applicable Methods of Committee D19 onWa
8、terD 3370 Practices for Sampling Water from Closed ConduitsD 3856 Guide for Good Laboratory Practices in Laborato-ries Engaged in Sampling and Analysis of WaterD 5810 Standard Guide for Spiking into Aqueous SamplesD 5847 Standard Practice for the Writing Quality ControlSpecifications for Standard Te
9、st Methods for Water Analy-sis3. Terminology3.1 DefinitionsFor definition of terms used in the testmethods, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 ion chromatographya form of liquid chromatogra-phy in which ionic constituents are separated by ion exchang
10、ethen detected by an appropriate detection means, typicallyconductance.3.2.2 eluentthe ionic mobile phase used to transport thesample through the chromatographic system.3.2.3 analytical columnthe ion exchange column used toseparate the ions of interest according to their retentioncharacteristics pri
11、or to detection.3.2.4 guard columna column used before the analyticalcolumn to protect it from contaminants, such as particulates orirreversibly retained material.3.2.5 analytical column seta combination of one or moreguard columns, followed by one or more analytical columnsused to separate the ions
12、 of interest.All of the columns in seriesthen contribute to the overall capacity and resolution of theanalytical column set.3.2.6 suppressor devicean ion exchange based device thatis placed between the analytical column set and the conduc-tivity detector. Its purpose is to minimize detector response
13、 tothe ionic constituents in the eluent, in order to lower back-ground conductance; and at the same time enhance the con-ductivity detector response of the ions of interest.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee
14、D19.05 on InorganicConstituents in Water.Current edition approved Jan. 1, 2005. Published January 2005.Originally approved in 2000. Last previous edition approved in 2000 asD 6581 00.2U.S. EPA Method 300.1, Cincinnati, OH, 1997.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or
15、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.7 resolutionth
16、e ability of an analytical column toseparate the method analytes under specific test conditions.4. Summary of Test Method4.1 Oxyhalides (chlorite, bromate, and chlorate) and bro-mide in raw water, finished drinking water and bottled waterare determined by ion chromatography. A sample (200 L) isinjec
17、ted into an ion chromatograph and the pumped eluent(sodium carbonate) sweeps the sample through the analyticalcolumn set. Here, anions are separated from the sample matrixaccording to their retention characteristics, relative to theanions in the eluent.The separated anions in the eluent stream then
18、pass througha suppressor device, where all cations are exchanged forhydronium ions. This converts the eluent to carbonic acid, thusreducing the background conductivity. This process also con-verts the sample anions to their acid form, thus enhancing theirconductivity. The eluent stream then passes t
19、hrough a conduc-tivity cell, where they are detected. A chromatographic inte-grator or appropriate computer-based data system is typicallyused for data presentation.4.2 The anions are identified based on their retention timescompared to known standards. Quantification is accomplishedby measuring ani
20、on peak areas and comparing them to theareas generated from known standards.5. Significance and Use5.1 The oxyhalides chlorite, chlorate, and bromate areinorganic disinfection by-products (DBPs) of considerablehealth risk concern worldwide. The occurrence of chlorite andchlorate is associated with t
21、he use of chlorine dioxide, as wellas hypochlorite solutions used for drinking water disinfection.The occurrence of bromate is associated with the use of ozonefor disinfection, wherein naturally occurring bromide is oxi-dized to bromate. Bromide is a naturally occurring precursor tothe formation of
22、bromate.6. Interferences6.1 Positive errors can be caused by progressive oxidationof residual hypochlorite and/or hypobromite in the sample tothe corresponding chlorate and bromate. Furthermore, chloritecan also be oxidized to chlorate, causing negative errors forchlorite and positive errors for chl
23、orate. These interferences areeliminated by the sample preservation steps outlined in 8.5.Chloride present at 200 mg/L and carbonate present at 300mg/L can interfere with bromate determination. These interfer-ences can be minimized, or eliminated, by the sample pretreat-ment steps outlined in 8.6. F
24、luoride and low molecular weightmonocarboxylic acids, present at mg/L concentrations, mayinterfere with the quantitation of chlorite and bromate.7. Apparatus7.1 Ion Chromatography ApparatusAnalytical systemcomplete with all required accessories, including eluent pump,injector, syringes, columns, sup
25、pressor, conductivity detector,data system and compressed gasses.7.1.1 Eluent Pumpcapable of delivering 0.25 to 5 mL/minof eluent at a pressure of up to 4000 psi.7.1.2 Injection ValveA low dead-volume switching valvethat will allow the loading of a sample into a sample loop andsubsequent injection o
26、f the loop contents into the eluentstream. A loop size of up to 200 L may be used withoutcompromising the resolution of early eluting peaks, such aschlorite and bromate.7.1.3 Guard ColumnAnion exchange column typicallypacked with the same material used in the analytical column,e.g., Dionex IonPac AG
27、9-HC, or equivalent. The purpose ofthis column is to protect the analytical column from particulatematter and irreversibly retained material.7.1.4 Analytical ColumnAnion exchange column capableof separating the ions of interest from each other, as well asfrom other ions which commonly occur in the s
28、ample matrix,e.g., Dionex IonPac AS9-HC (4 mm ID), or equivalent. Theseparation shall be at least as good as that shown in Fig. 2. Theuse of 2 mm ID AS9-HC column, in conjunction with a 50 Lsample loop, may improve the peak shape for early elutinganions, such as chlorite and bromate.NOTE 1The Analyt
29、ical Column Set (see 3.2.3) should be able to givebaseline resolution of all anions, even for a 200 L injection containing upto 200 mg/L, each, of common anions, such as chloride, bicarbonate, andsulfate.7.1.5 Suppressor DeviceA suppressor device based uponcation exchange principles. In this method,
30、 a membrane-basedself regenerating suppressor device, Dionex ASRS-ULTRA,was used. An equivalent suppressor device may be usedprovided that comparable method detection limits are achievedand that adequate baseline stability is attained.7.1.6 Conductivity DetectorA low-volume, flow through,temperature
31、stabilized conductivity cell equipped with a metercapable of reading from 0 to 1000 S/cm on a linear scale.7.1.7 Data SystemA chromatographic integrator orcomputer-based data system capable of graphically presentingthe detector output signal versus time, as well as presenting theintegrated peak area
32、s.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are
33、available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without reducing theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformi
34、ngto Specification D 1193, Type I. Other reagent water types maybe used, provided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffecting the bias and precision of the determination.8.3 Eluent, Concentrate (90.0 mM Sodium Carbonate)Dissolve 9
35、.540 g of sodium carbonate in 1000 mL of water.4“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see “Analar Standards for Laboratory Chemicals,”by BDH Ltd., Poole
36、, Dorset, U.K., and the “United States Pharmacopoeia.”D 6581 00 (2005)28.4 Eluent, Analysis (9.0 mM Sodium Carbonate)Dilute100.0 mL of Eluent Concentrate (8.3) to 1.000 L with water.8.4.1 The Eluent Analysis solution (9.0 mM Sodium Car-bonate) must be purged for 10 minutes with helium prior to useto
37、 remove dissolved gasses in order to ensure optimal systemperformance.8.5 Ethylenediamine (EDA) Preservation Solution (50.0g/L)Dilute 11.2 mL of ethylenediamine (99%) to 200 mLwith reagent water. Prepare this solution fresh monthly. Add1.00 mL of this solution per 1.000 L of blank, standard orsample
38、 to produce a final EDA concentration of 50 mg/L.FIG. 1 Chromatogram of a Standard Containing Low g/L Oxyhalides, and Bromide, in the Presence of Common Inorganic Anions. SeeTable 1 for Analysis Conditions.FIG. 2 Chromatogram of Low g/L Oxyhalides, and Bromide, in Simulated Drinking Water. See Table
39、 1 for Analysis Conditions.D 6581 00 (2005)38.6 SPE Sample Preatment Cartridges Chloride presentat 200 mg/L and carbonate present at 300 mg/L caninterfere with bromate determination. H+form and Ag+formcation exchange SPE cartridges can be used to minimize thecarbonate and chloride interferences, res
40、pectively, if required.Dionex OnGuard-H and OnGuard-Ag cartridges have beenshown to be suitable for this application.5The use of thesepretreatment cartridges will effect recoveries for bromide,requiring that it be analyzed in a separate run.8.7 Suppressor Regenerant Solution If a suppressor re-quiri
41、ng chemical regeneration is used, the regenerant solutionis prepared by cautiously adding 3.00 mL of concentratedsulfuric acid (sp. gr. 1.84) to 4.000 L of water. If an Anion SelfRegenerating Suppressor is used, it should be operated in theexternal water mode.8.8 Standard Solutions, Stock (1.00 mL =
42、 1.00 mg)Purchase certified solutions or prepare stock standard solutionsfrom the following salts, as described below:8.8.1 Bromate (BrO3) Solution, Stock (1.00 mL = 1.00 mgBrO3)Dissolve 1.180 g of sodium bromate (NaBrO3)inwater and dilute to 1.000 L.8.8.2 Bromide (Br) Solution, Stock (1.00 mL = 1.0
43、0 mgBr)Dissolve 1.288 g of sodium bromide (NaBr) in waterand dilute to 1.000 L.8.8.3 Chlorate (ClO3) Solution, Stock (1.00 mL = 1.00 mgC1O3)Dissolve 1.275 g of sodium chlorate (NaClO3)inwater and dilute to 1.000 L.8.8.4 Chlorite (ClO2) Solution, Stock (1.00 mL = 1.00 mgClO2)Dissolve 1.680 g of sodiu
44、m chlorite (NaClO2)inwater and dilute to 1.000 L. Note that as sodium chlorite isusually available only as an 80% technical grade salt, the 80%purity is accounted for in the 1.680 g weight cited above. If analternate purity is used, make an appropriate adjustment in theweight of salt used after dete
45、rmining the exact percentage ofNaClO2, which can be done using an iodometric titrationprocedure.2 ,68.9 Reagent BlankAdd 1.00 mL of EDA PreservationSolution (8.5) to 1.000 L of reagent water.9. Precautions9.1 These methods address the determination of very lowconcentrations of selected anions. Accor
46、dingly, every precau-tion should be taken to ensure the cleanliness of samplecontainers as well as other materials and apparatus that come incontact with the sample.10. Sampling and Sample Preservation10.1 Collect the sample in accordance with Practice D 3370,as applicable.10.2 Immediately upon taki
47、ng the sample, sparge it with aninert gas (e.g., nitrogen, argon or helium) for 5 minutes toremove active gases such as chlorine dioxide or ozone. Add1.00 mL of EDA Preservation Solution (8.5) per 1.000 litre ofsample to prevent conversion of residual hypochlorite orhypobromite to chlorate or bromat
48、e. This also prevents metalcatalyzed conversion of chlorite to chlorate. The oxyhalides insamples preserved in this manner are stable for at least 14 dayswhen stored in amber bottles at 4C.711. Quality Control11.1 Before this test is applied to analyzing unknownsamples, the analyst should establish
49、quality control proce-dures as recommended in Guide D 3856.11.2 The laboratory using this test should perform an initialdemonstration of laboratory capability. Analyze seven repli-cates of an Initial Demonstration of Performance (IDP) solu-tion. The IDP solution contains method analytes of knownconcentration, prepared from a different source to the calibra-tion standards, used to fortify reagent water, which alsocontains a final EDA concentration of 50 mg/L (8.5). Ideally,the IPD solution should be prepared by an independent source
