1、Designation: D3859 15Standard Test Methods forSelenium in Water1This standard is issued under the fixed designation D3859; 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 indicates
2、 the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of dissolvedand total recoverable selenium in most waters and wastewaters.Both test methods utilize atomic absorption proc
3、edures, asfollows:SectionsTest Method AGaseous Hydride AAS2, 3716Test Method BGraphite Furnace AAS 17261.2 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 the
4、 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 Hydride AAS2, 31to20g/LTest Method BGraphite Furnace AAS 2 to 100 g/LThese ranges may be
5、extended (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.
6、 The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.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 th
7、is standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see 11.12 and 13.14.2. Referenced Documents2.1 ASTM Standards:4D1129 Terminology Relating to WaterD1193 Specification for Reagent
8、WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD4841 Practice for Estimati
9、on of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD5673 Test Method for Elements in Water by InductivelyCoupled PlasmaMass SpectrometryD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Wat
10、er Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in these test methods,refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total recoverable selenium, na descriptive termrelating to the selenium forms recovered in the acid-digestionprocedur
11、e specified in these test methods.4. Significance and Use4.1 In most natural waters selenium concentrations seldomexceed 10 g/L. However, the runoff from certain types ofseleniferous soils at various times of the year can produceconcentrations as high as several hundred micrograms per litre.Addition
12、ally, industrial contamination can be a significantsource of selenium in rivers and streams.4.2 High concentrations of selenium in drinking water havebeen suspected of being toxic to animal life. Selenium is apriority pollutant and all public water agencies are required tomonitor its concentration.1
13、These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved March 15, 2015. Published April 2015. Originallyapproved in 1984. Last previous edition approved in 2008 as
14、D3859 08. DOI:10.1520/D3859-15.2Lansford, M., McPherson, E. M., and Fishman, M. J., Atomic AbsorptionNewsletter, Vol 13, No. 4, 1974, pp. 103105.3Pollack, E. N., and West, S. J., Atomic Absorption Newsletter , Vol 12, No. 1,1973, pp. 68.4For referenced ASTM standards, visit the ASTM website, www.ast
15、m.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box
16、 C700, West Conshohocken, PA 19428-2959. United States14.3 These test methods determine the dominant species ofselenium reportedly found in most natural and wastewaters,including selenities, selenates, and organo-selenium com-pounds.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in a
17、ll 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.5Other grades may be used, pro-vided it is ascertained that the reagent is of suffi
18、ciently 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 D1193, Type I. Other reagent water types maybe used provided it is first ascer
19、tained 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 Collect the samples in accordance with PracticesD3370. Take the
20、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 D4841.6.2 When determining only dissolved selenium, filter thesample th
21、rough 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 within 15minutes of collecting the sample.NOTE 1Alternatively, the pH may be adjusted in the
22、 laboratory if thesample is returned within 14 days. However, acid must be added at least24 hours before analysis to dissolve any metals that adsorb to the containerwalls. This could reduce hazards of working with acids in the field whenappropriate.TEST METHOD AGASEOUS HYDRIDE AAS7. Scope7.1 This te
23、st 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 water, wastewater, and brines.
24、 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 flameAAS.8.1.1 The conversion
25、 consists of (1) decomposition andoxidation to selenium (VI), (2) reduction to selenium (IV), and(3) 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 from asimple concentration
26、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. Interferences9.1 Mercury and arse
27、nic 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.610.2 Atomic Absorption Sp
28、ectrophotometerThe 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 desiredwavelength, an adjustable sli
29、t, 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 Discharge LampThe sensi-ti
30、vity of selenium to atomic absorption spectroscopy is gener-ally improved with this lamp, although some hollow-cathodelamps produce equivalent results. The intensity and stability ofthe lamp shall be adequate to determine selenium in the rangefrom 1 to 20 g/L.10.2.2 Recorder or Digital Readout, or B
31、othAnymultirange, variable-speed recorder, or digital readout acces-sory that is compatible with the atomic absorption detectionsystem, is suitable.10.2.3 The manufacturers instructions are to be followedfor all instrument parameters.5Reagent Chemicals, American Chemical Society Specifications, Amer
32、icanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USP
33、C), Rockville,MD.6Astatic system, such as one using a balloon, has been found satisfactory for thispurpose. See McFarren, E. F., “New, Simplified Method for Metal Analysis,”Journal of American Water Works Association, Vol 64, 1972, p. 28.D3859 15210.3 Gas System:10.3.1 See 11.14 for materials for th
34、e gas system.10.3.2 Pressure-Reducing ValvesPressure-reducing valvesshall be capable of maintaining argon pressure at 275 kPa (40psi) and hydrogen pressure at 138 kPa (20 psi).10.4 Additional Equipment:10.4.1 Flask HeaderThe flask header shall consist of athree-hole rubber stopper into which is inse
35、rted:10.4.1.1 A sintered-glass aeration tube for the argon sweepgas,10.4.1.2 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 2Instead of the gas chromatographic-type septum
36、, 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 install the reaction-flask hea
37、der inseries with the auxiliary oxidant line and the burner. Plastic orother metals may be substituted if proven acceptable.FIG. 1 Apparatus for Selenium DeterminationD3859 15310.4.3 TubingAny commercially available plastic tubingthat is not susceptible to attack by hydrochloric acid, seleniumhydrid
38、e, or other gases from the 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
39、trap suitable to prevent carryover 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. Howeve
40、r, precaution-ary measures could generally preclude the use of this device,since 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 may be used. Conical and re
41、-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 dilute to 1 L.11.2 Hydro
42、chloric 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 acid to water.11.5 Methyl Oran
43、ge 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/L)Dissolve0.3 g of potassiu
44、m permanganate (KMnO4) in water and diluteto1L.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 cautiouslyevaporate to dryness. Redissolve
45、with HCl (1 + 99) and diluteto 1 L with the same acid solution.11.9.1 A purchased metal selenium stock solution of appro-priate known purity is also acceptable.11.10 Selenium Solution, Intermediate (1.00 mL = 10 gselenium)Dilute 5 mL of the selenium stock solution to 500mL with HCl (1 + 99).11.11 Se
46、lenium Solution, Standard (1.00 mL = 0.10 gselenium)Dilute 10 mL of 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 prepare 100 mL of the Selenium Standard Solution.11.12 Sodium Bo
47、rohydride Solution (4 g/100 mL)Dissolve4gofsodium borohydride (NaBH4)and2gofsodium hydroxide in water and dilute to 100 mL. Prepare freshweekly. (WarningSodium borohydride reacts strongly withacids.)11.13 Sodium Hydroxide Solution (4 g/L)Dissolve4gofsodium hydroxide (NaOH) in water and dilute to 1 L
48、.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 Transfer 0.0, 0.5, 1.0, 2.0, 5.0, and 10.0-mL portions ofthe standard se
49、lenium solution (1.0 mL = 0.10 g Se) (11.11)tofreshly washed 250-mL reaction flasks. Adjust the volume to50 mL with water. Analyze at least six working standardscontaining concentrations of selenium that bracket the ex-pected sample concentration, prior to analysis of samples, tocalibrate the instrument.12.2 Proceed as directed in 13.3 13.15.12.3 Calibrate the spectrophotometer to output microgramsof selenium directly, if provided with this capability or preparea calibration curve by plotting absorbance (or recorder scaleread
