ASTM D3859-2008 Standard Test Methods for Selenium in Water《水中硒含量的标准试验方法》.pdf

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1、Designation: D 3859 08Standard Test Methods forSelenium in Water1This standard is issued under the fixed designation D 3859; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicat

2、es the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of dissolvedand total recoverable selenium in most waters and wastewaters.Both test methods utilize atomic absorption pro

3、cedures, asfollows:SectionsTest Method AGaseous Hydride AAS27to16Test Method BGraphite Furnace AAS 17 to 261.2 These test methods are applicable to both inorganic andorganic forms of dissolved selenium. They are applicable alsoto particulate forms of the element, provided that they aresolubilized in

4、 the appropriate acid digestion step. However,certain selenium-containing heavy metallic sediments may notundergo digestion.1.3 These test methods are most applicable within thefollowing ranges:Test Method AGaseous HydrideAAS21to20g/LTest Method BGraphite FurnaceAAS2 to 100 g/LThese ranges may be ex

5、tended (with a corresponding loss inprecision) by decreasing the sample size or diluting the originalsample, but concentrations much greater than the upper limitsare more conveniently determined by flame atomic absorptionspectrometry.1.4 The values stated in SI units are to be regarded asstandard. N

6、o other units of measurement are included in thisstandard.1.5 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 practices and determine the applica-bil

7、ity of regulatory limitations prior to use. For specific hazardstatements, see 11.12 and 13.14.2. Referenced Documents2.1 ASTM Standards:3D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Com

8、mittee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD 5810 G

9、uide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in these test methods,refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Sta

10、ndard:3.2.1 total recoverable seleniuman arbitrary analyticalterm relating to the recoverable forms of selenium that aredeterminable by the digestion procedures included in these testmethods.4. Significance and Use4.1 In most natural waters selenium concentrations seldomexceed 10 g/L. However, the r

11、unoff from certain types ofseleniferous soils at various times of the year can produceconcentrations as high as several hundred micrograms per litre.Additionally, industrial contamination can be a significantsource of selenium in rivers and streams.4.2 High concentrations of selenium in drinking wat

12、er havebeen suspected of being toxic to animal life. Selenium is apriority pollutant and all public water agencies are required tomonitor its concentration.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on Inorgan

13、icConstituents in Water.Current edition approved Oct. 1, 2008. Published October 2008. Originallyapproved in 1984. Last previous edition approved in 2003 as D 3859 03.2Lansford, M., McPherson, E. M., and Fishman, M. J., Atomic AbsorptionNewsletter, Vol 13(4), 1974, pp. 103105. Pollack, E. N., and We

14、st, S. J., AtomicAbsorption Newsletter , Vol 12(1), 1973, pp. 68.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM webs

15、ite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 These test methods determine the dominant species ofselenium reportedly found in most natural and wastewaters,including selenities, selenates, and organo-selenium com-pounds.5.

16、Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.4Other grades may b

17、e used, pro-vided it is ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of thedetermination.5.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specification D 1193, Type I

18、. 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 test method. Type IIwater was specified at the time of round robin testing of thistest method.6. Sampling6.1

19、 Collect the samples in accordance with PracticesD 3370. Take the samples in acid-washed TFE-fluorocarbon orglass bottles. Other types of bottles may be used for sampling,but should be checked for selenium absorption. The holdingtime for the samples may be calculated in accordance withPractice D 484

20、1.6.2 When determining only dissolved selenium, filter thesample through a 0.45-m membrane filter as soon as possibleafter sampling. Add HNO3to the filtrate to bring the pH to2.0.6.3 When determining total recoverable selenium, addHNO3to the unfiltered sample to a pH of 2.0.TEST METHOD AGASEOUS HYDR

21、IDE AAS7. Scope7.1 This test method covers the determination of dissolvedand total recoverable selenium in the range from 1 to 20 g/L.The range may be extended by decreasing the sample size ordiluting the original sample.7.2 This test method has been used successfully withreagent water, natural wate

22、r, wastewater, and brines. Theinformation on precision may not apply to waters of othermatrices.8. Summary of Test Method8.1 The determination consists of the conversion of sele-nium in its various forms to gaseous selenium hydride (hydro-gen selenide), with the subsequent analysis of the gas by fla

23、meAAS.8.1.1 The conversion consists of (a) decomposition andoxidation to selenium (VI), (b) reduction to selenium (IV), and(c) final reduction to selenium hydride.8.1.2 The absorbance is determined at 196.0 nm in ahydrogen-argon (air-entrained) flame.8.2 Sample concentrations are obtained directly f

24、rom asimple concentration versus absorbance calibration curve.8.3 Total recoverable selenium is determined by treating theentire sample as the procedure indicates, and the dissolvedselenium is determined by treating the filtrate after the sampleis filtered through a 0.45-m membrane filter.9. Interfe

25、rences9.1 Mercury and arsenic at concentrations greater than 500g/L and greater than 100 g/L, respectively, may inhibit theformation of selenium hydride.10. Apparatus10.1 An apparatus similar to that depicted in Fig. 1, with thecomponents specified in 10.2-10.4.8, is recommended for thistest method.

26、510.2 Atomic Absorption SpectrophotometerThe instru-ments shall consist of an atomizer and burner, suitable pressureand flow regulation devices capable of maintaining constantdiluent and fuel pressure for the duration of the test, a seleniumlamp, an optical system capable of isolating the desiredwav

27、elength, an adjustable slit, a photomultiplier tube or otherphotosensitive devices such as a light measuring and amplify-ing device, and a readout mechanism for indicating the amountof absorbed radiation.Abackground corrector may be used, butis not absolutely essential.10.2.1 Selenium Electrodeless

28、Discharge LampThe sen-sitivity of selenium to atomic absorption spectroscopy isgenerally improved with this lamp, although some hollow-cathode lamps produce equivalent results. The intensity andstability of the lamp shall be adequate to determine selenium inthe range from 1 to 20 g/L.10.2.2 Recorder

29、 or Digital Readout, or BothAny multi-range, variable-speed recorder, or digital readout accessory thatis compatible with the atomic absorption detection system, issuitable.10.2.3 The manufacturers instructions are to be followedfor all instrument parameters.10.3 Gas System:10.3.1 See 11.14 for mate

30、rials for the gas system.10.3.2 Pressure-Reducing ValvesPressure-reducingvalves shall be capable of maintaining argon pressure at 40psig (275 kPa) and hydrogen pressure at 20 psig (138 kPa).10.4 Additional Equipment:10.4.1 Flask HeaderThe flask header shall consist of athree-hole rubber stopper into

31、 which is inserted:10.4.1.1 A sintered-glass aeration tube for the argon sweepgas,4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for La

32、boratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.5Astatic system, such as one using a balloon, has been found satisfactory for thispurpose. See McFarren, E. F., “New, Simplified Method

33、 for Metal Analysis,”Journal of American Water Works Association, Vol 64, 1972, p. 28.D385908210.4.1.2 A small gas chromatographic-type septum (5 to 10mm in diameter), for injection of the borohydride solution, and10.4.1.3 A glass outlet tube for the reaction gases to exit.NOTE 1Instead of the gas c

34、hromatographic-type septum, a moresecure seal may be obtained by using a glass tube with a septum cap.These items are commercially available on an individual basis. A differentheader may be used if proven reliable.10.4.2 Fittings and AdaptersStainless steel fittings andadapters shall be used to inst

35、all the reaction-flask header inseries with the auxiliary oxidant line and the burner. Plastic orother metals may be substituted if proven acceptable.10.4.3 TubingAny commercially available plastic tubingthat is not susceptible to attack by hydrochloric acid, seleniumhydride, or other gases from the

36、 reaction mixture is acceptable.Poly(vinyl chloride) tubing has been found acceptable.10.4.4 Gas-Flow RegulatorA suitable in-line gas-flowvalve shall be used to adjust the flow of argon to thereaction-flask header.10.4.5 Water Trap (optional)Any commercially availableglass trap suitable to prevent c

37、arryover moisture from going tothe burner is acceptable.10.4.6 One-Way Gas Check Valve (optional)A one-waycheck valve can be installed in series with the water trap andburner to prevent hydrogen from back flowing to the generat-ing flask whenever samples are changed. However, precaution-ary measures

38、 could generally preclude the use of this device,FIG. 1 Apparatus for Selenium DeterminationD3859083since only when the flask header is removed for prolongedperiods would there be significant hydrogen back flow.10.4.7 Reaction Flasks, 250-mL spoutless beakers, or theirequivalent, with graduations ma

39、y be used. Conical and re-stricted neck flasks do not perform as reliably as spoutlessbeakers.10.4.8 Hypodermic Syringe, 2-mL capacity with a 50-mmneedle.11. Reagents and Materials11.1 Calcium Chloride Solution (30 g/L)Commerciallypurchase or dissolve 30 g of calcium chloride (CaCl22H2O) inwater and

40、 dilute to 1 L.11.2 Hydrochloric Acid (sp gr 1.19), concentrated hydro-chloric acid (HCl).11.3 Hydrochloric Acid (1 + 1)Add 1 volume of HCl (spgr 1.19) to 1 volume of water. Always add acid to water.11.4 Hydrochloric Acid (1 + 99)Add 1 volume of HCl (spgr 1.19) to 99 volumes of water. Always add aci

41、d to water.11.5 Methyl Orange Indicator Solution (25 mg/100 mL)Dissolve 25 mg of methyl orange in 100 mL of water.11.6 Nitric Acid (sp gr 1.42), concentrated nitric acid(HNO3).11.7 Nitric Acid (1 + 99)Add 1 volume of HNO3(sp gr1.42) to 99 volumes of water.11.8 Potassium Permanganate Solution (0.3 g/

42、L) Dis-solve 0.3 g of potassium permanganate (KMnO4) in water anddilute to 1 L.11.9 Selenium Solution, Stock (1.00 mL = 1.00 mgselenium)Accurately weigh 1.000 g of gray elemental sele-nium and place in a small beaker. Add 5 mL of HNO3(sp gr1.42). Warm until the reaction is complete, then cautiouslye

43、vaporate to dryness. Redissolve with HCl (1 + 99) and diluteto 1 L with the same acid solution.11.9.1 Alternatively, certified selenium stock solutions arecommercially available through chemical supply vendors andmay be used.11.10 Selenium Solution, Intermediate (1.00 mL = 10 gselenium)Dilute 5 mL o

44、f the selenium stock solution to 500mL with HCl (1 + 99).11.11 Selenium Solution, Standard (1.00 mL = 0.10 gselenium)Dilute 10 mLof the selenium intermediate solutionto 1000 mL with HCl (1 + 99). Prepare fresh daily and store ina TFE-fluorocarbon or other acceptable container. To minimizewaste only

45、prepare 100 mL of the Selenium Standard Solution.11.12 Sodium Borohydride Solution (4 g/100 mL) Dis-solve4gofsodium borohydride (NaBH4)and2gofsodiumhydroxide in water and dilute to 100 mL. Prepare fresh weekly.Warning: Sodium borohydride reacts strongly with acids.11.13 Sodium Hydroxide Solution (4

46、g/L)Dissolve4gofsodium hydroxide (NaOH) in water and dilute to 1 L.11.14 Gases:11.14.1 Argon (nitrogen may be used in place of argon)Standard, commercially available argon is the usual diluent.11.14.2 HydrogenStandard, commercially available hy-drogen is the usual fuel.12. Standardization12.1 Transf

47、er 0.0, 0.5, 1.0, 2.0, 5.0, and 10.0-mL portions ofthe standard selenium solution (1.0 mL = 0.10 g Se) to freshlywashed 250-mL reaction flasks. Adjust the volume to 50 mLwith water.12.2 Proceed as directed in 13.3-13.15.12.3 Prepare a calibration curve by plotting absorbance (orrecorder scale readin

48、gs) versus micrograms of selenium onlinear graph paper. Alternatively, if provided with this capabil-ity, calibrate the spectrophotometer to output micrograms ofselenium directly.13. Procedure13.1 It is emphasized that careful control of pH, oxidantconcentration, temperature, and time are imperative

49、 if accurateand precise selenium determinations are to be obtained.13.2 For each sample, transfer 50 mL or less (to contain notmore than 1.0 g selenium) to a freshly washed 250-mLreaction flask. Make up to 50 mL with water if necessary.13.3 To each sample, standard, and blank, add a few dropsof methyl orange solution, 0.5 mL of CaCl2solution and threeor four boiling stones.13.4 Adjust the pH to the red end point of methyl orange(pH = 3.1) with HCl (1 + 99) or NaOH solution (4 g/L). Add0.5 mL of HCl (1 + 99) in excess. A pH meter may be