1、Designation: D 1687 02 (Reapproved 2007)e1Standard Test Methods forChromium in Water1This standard is issued under the fixed designation D 1687; 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
2、 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 Defense.e1NOTEThe table in 1.1 and Sections 15.5, 24.5, and 33.3 were updated edit
3、orially in August 2007.1. Scope1.1 These test methods cover the determination of hexava-lent and total chromium in water. Three test methods areincluded as follows:Test Method ConcentrationRangeSectionsAPhotometric Diphenyl-carbohydrazide0.01 to 0.5mg/L7-15BAtomicAbsorption, Direct0.1to10mg/L16-24CA
4、tomic Absorption,Graphite Furnace5to100g/L25-331.2 Test Method A is a photometric method that measuresdissolved hexavalent chromium only. Test Methods B and Care atomic absorption methods that are generally applicable tothe determination of dissolved or total recoverable chromiumin water without reg
5、ard to valence state.1.3 Test Method A has been used successfully with reagentgrade water Types I, II, and III, tap water, 10 % NaCl solution,treated water from a synthetic organic industrial plant thatmeets National Pollution Discharge Elimination System (NP-DES) permit requirements, and EPA-extrac
6、tion procedureleachate water, process water, lake water, effluent treatment,that is, lime neutralization and precipitation of spent pickleliquor and associated rinse water from stainless steel pickling.Test Method C has been used successfully with reagent water,stock scrubber water, lake water, filt
7、ered tap water, river water,well water, production plant water, and a condensate from amedium BTU coal gasification process. Matrices used, exceptfor reagent water, are not available for Test Method B. It is theusers responsibility to ensure the validity of these test methodsfor waters of untested m
8、atrices.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 practices and determine the applica-bility of regulatory limitations prior to use. For sp
9、ecific hazardstatements, see 4.2 and Note 5 and Note 6.2. Referenced Documents2.1 ASTM Standards:2D 858 Test Methods for Manganese in WaterD 1066 Practice for Sampling SteamD 1068 Test Methods for Iron in WaterD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam
10、 in Closed Conduits3D 1193 Specification for Reagent WaterD 1688 Test Methods for Copper in WaterD 1691 Test Methods for Zinc in WaterD 1886 Test Methods for Nickel in WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3370 Practices for
11、 Sampling Water from Closed ConduitsD 3557 Test Methods for Cadmium in WaterD 3558 Test Methods for Cobalt in WaterD 3559 Test Methods for Lead in WaterD 3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD 4691 Practice for Measuring Elements i
12、n Water by FlameAtomic Absorption SpectrophotometryD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water A
13、nalysisE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-eters1These test methods are under the jurisdiction of ASTM Committee D19 onWater
14、 and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved Aug. 1, 2007. Published August 2007. Originallyapproved in 1959. Last previous edition approved in 2002 as D 1687 02.2For referenced ASTM standards, visit the ASTM website, www.astm.o
15、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3
16、. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 Laboratory Control Sample, na solution with thecertified concentration(s) of the analytes.4. Significance and Use4.1 Hexavalent chromiu
17、m salts are used extensively inmetal finishing and plating applications, in anodizing alumi-num, and in the manufacture of paints, dyes, explosives, andceramics. Trivalent chromium salts are used as mordants intextile dyeing, in the ceramic and glass industry, in the leatherindustry as a tanning age
18、nt, and in photography. Chromiummay be present in wastewater from these industries and mayalso be discharged from chromate-treated cooling waters.4.2 The hexavalent state of chromium is toxic to humans,animals, and aquatic life. It can produce lung tumors wheninhaled and readily induces skin sensiti
19、zation. However, it isnot known whether cancer will result from ingestion ofchromium in any of its valence states.5. 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 Committ
20、ee on AnalyticalReagents of the American Chemical Society4where suchspecifications are available. Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Purity of WaterUnless
21、otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I, II, or III water. Type I ispreferred and more commonly used. Type II water wasspecified at the time of round robin testing of these testmethods.NOTE 1The user must ensure the
22、type of reagent water chosen issufficiently free of interferences. The water should be analyzed using thetest method.6. Sampling6.1 Collect the sample in accordance with the applicableASTM standard as follows: Practice D 1066, SpecificationD 1192, or Practices D 3370. The holding time for the sample
23、smay be calculated in accordance with Practice D 4841.6.2 Samples to be analyzed by Test Method A should bestabilized upon collection by addition of sodium hydroxidesolution to a pH greater than or equal to 8, or analyzedimmediately. Minor delays in stabilization or analyses ofsamples containing sul
24、fur reduction compounds can producesignificant loss in hexavalent chromium. Acidic samples con-taining hypobromite, persulfate, or chlorine could oxidizetrivalent chromium, if present, to hexavalent form upon pres-ervation, resulting in a positive interference. When the pres-ence of these oxidizing
25、compounds is suspected, samplesshould not be preserved but analyzed immediately. It will beevident that in this case, the simultaneous presence of reducingcompounds could not be anticipated.6.3 Samples to be analyzed by Test Methods B and C shallbe preserved by addition of HNO3(sp gr 1.42) to pH of
26、2 or lessimmediately at the time of collection, normally about 2 mLHNO3/L. If only dissolved chromium is to be determined, thesample shall be filtered through a 0.45-m membrane filterbefore acidification.TEST METHOD APHOTOMETRICDIPHENYLCARBOHYDRAZIDE7. Scope7.1 This test method covers the determinat
27、ion of dissolvedhexavalent chromium in water.7.2 The test method is applicable in the range from 0.01 to0.5 mg/L chromium. The range may be extended by appropri-ate sample dilution.7.3 This test method has been used successfully withreagent grade water Types I, II, and III, tap water, 10 % NaClsolut
28、ion, treated water from a synthetic organic industrial plantthat meets NPDES permit requirements, EPA-extraction pro-cedure leachate water, process water, lake water, effluent fromtreatment that is, lime neutralization and precipitation of spentpickle liquor and associated rinse water from stainless
29、 steelpickling. It is the responsibility of the user to ensure thevalidity of the test method to waters of untested matrices.8. Summary of Test Method8.1 Hexavalent chromium reacts with 1.5-diphenylcarbohydrazide (s-diphenylcarbazide) in an acid me-dium to produce a reddish-purple color. The intensi
30、ty of thecolor formed is proportional to the hexavalent chromiumconcentration.9. Interferences9.1 Vanadium, titanium, or iron present at concentrations of5 mg/L yield a 10 to 30 % reduction in recovery of chromium.Copper at 100 mg/L yields a 20 to 30 % reduction in recoveryin the presence of sulfate
31、. Mercury gives a blue-purple color,but the reaction is not very sensitive at the pH employed for thetest.9.2 Nitrite concentrations in excess of 10 mg/Las NO2yieldlow test results. Sulfamic acid may be added (;10.1 g) prior tothe addition of diphenylcarbazide solution to minimize nitriteinterferenc
32、e. Add sulfamic acid only when the presence ofnitrite has been positively established. Excess sulfamic aciditself creates a slightly positive interference.9.3 Sulfide and sulfite reduce chromate in an acid mediumto give low results.9.4 Several sample matrices have been identified whichproduce a yell
33、ow-orange complex that interferes with thisquantification. When this occurs, it may be remedied by4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar
34、 Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 1687 02 (2007)e12inverting the indicator-buffer sequence. In these cases theanalyst should evaluate the matrix effec
35、t with the additions ofspikes. (Guide D 5810)9.5 Although each interferent has been reported, most of thecommon interferences are eliminated by the preservationprocedure at the time of collection. The potentially interferingmetals are precipitated and the reducing effect of sulfurcompounds has been
36、overcome.10. Apparatus10.1 PhotometerSpectrophotometer or filter photometersuitable for use at 540 nm and equipped with a cell having aminimum path length of 10 mm. The photometers and photo-metric practice prescribed in this test method shall conform toPractice E60. Spectrophotometers and spectroph
37、otometricpractice shall conform to Practice E 275.11. Reagents11.1 Chromium Solution, Stock (1 mL = 0.10 mg Cr)Dissolve 0.2828 g of potassium dichromate (K2Cr2O7that hasbeen oven dried at 105C for 1 h) in water. Dilute to 1 L withwater.11.2 Chromium Solution, Standard (1 mL = 0.001 mg Cr)Dilute 10.0
38、 mL of chromium stock solution (see 11.1)to1Lwith water.11.3 Diphenylcarbazide Indicator SolutionDissolve 0.25g of powdered 1,5-diphenylcarbohydrazide in 100 mL ofacetone. Store in an amber glass-stoppered flask at 4C whennot in use. This solution is stable for about one week when keptrefrigerated.
39、Prepare fresh reagent when the solution becomesdiscolored.NOTE 2Allow the indicator solution to warm to room temperaturebefore use.11.4 Phosphoric Acid (1 + 1)Dilute 500 mL of concen-trated phosphoric acid (sp gr 1.69) to 1 L with water.11.5 Phosphoric Acid (1 + 19)Dilute 50 mL of concen-trated phos
40、phoric acid (sp gr 1.69) to 1 L with water.11.6 Sodium Hydroxide Solution (40 mg/L)Dissolve 40mg of sodium hydroxide (NaOH) in water. Cool and dilute to1 L. This solution is used for sample preservation.11.7 Sulfamic Acid(NH2SO3H)Crystals.12. Calibration12.1 Prepare a series of at least four standar
41、d solutionscontaining from 0 to 0.50 mg/L of chromium by dilutingmeasured volumes of the standard chromium solution (see11.2) to 100 mL with water in separate volumetric flasks.12.2 Transfer 50 mL of each prepared standard solution toseparate 125-mL Erlenmeyer flasks and proceed with 13.3-13.6.12.3
42、Prepare a calibration curve by plotting milligrams perliter of chromium versus absorbance on linear graph paper.12.4 A calibration curve must be prepared for each photom-eter. A recalibration must be made if any alterations of theinstrument are made or if new reagents are prepared. At theleast, a bl
43、ank and three chromium standard solutions must beanalyzed to verify the original test calibration each time the testis performed.13. Procedure13.1 Filter a portion of the sample through a 0.45-mmembrane filter and adjust the pH into the 8 to 8.5 range if itis greater than 8.5 with a few drops of the
44、 phosphoric acidsolution (1 + 19).13.2 Transfer 50.0 mL of the filtered sample, or a smalleraliquot of sample diluted to 50.0 mL, to a 125-mL Erlenmeyerflask.13.3 Add 2.0 mL of the diphenylcarbazide solution to eachsolution and swirl to mix.NOTE 3If the sample is colored, prepare a separate aliquot
45、asdescribed in 13.1 and 13.2. Add 2.0 mL of acetone instead of diphenyl-carbazide solution and proceed with 13.4 and 13.5. Use this solution as thesample blank.13.4 Immediately add 5.0 mL of phosphoric acid solution(1 + 1) to each solution and swirl to mix.13.5 Permit the solutions to stand 15 min f
46、or full colordevelopment. Measure the absorbance within 30 min after theaddition of the diphenylcarbazide solution at 540 nm with acell having a minimum path length of 10 mm.13.6 Determine milligrams per liter of chromium as Cr+6inthe test sample by referring the absorbance to the preparedcalibratio
47、n curve (see 12.3).14. Calculation14.1 Calculate the hexavalent chromium concentration asfollows:Cr16, mg/L 5 WS2 WB!50/S! (1)where:WS= chromium found in the sample, mg/L (see 13.6),WB= chromium found in the sample blank, mg/L (see13.6), andS = volume of sample used, mL (see 13.2).15. Precision and
48、Bias15.1 The collaborative test data were obtained on reagentgrade water Types I, II, and III, tap water, 10 % NaCl solution,treated water from a synthetic organic industrial plant whichmeets NPDES permit requirements, EPA-extraction procedureleachate water, process water, lake water, effluent from
49、treat-ment, that is, lime neutralization and precipitation of spentpickle liquor and associated rinse water from stainless steelpickling.15.2 Single-operator and overall precision of this testmethod within its designated range and recovery data for theabove waters for 16 laboratories, which include a total of 16operators analyzing each sample on three different days, isgiven in Table 1.15.3 Single-operator and overall precision of this testmethod within its designated range and recovery data for aprepared leachate water for 8 laboratories, which include ato
