ASTM_D_5281_-_98.pdf

Designation:D 5281 98Standard Test Method forCollection and Analysis of Hexavalent Chromium in AmbientAtmospheres1This standard is issued under the fixed designation D 5281;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 the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the collection and measurementof hexavalent chromium Cr(VI)in the ambient atmosphere.1.2 This test method collects and stabilizes atmospherichexavalent chromium using an alkaline impinger buffer solu-tion in a wet impingement sampling technique.Lead chromatePbCrO4,generally considered poorly soluble in water,issoluble in the impinger solution up to 940 g/L as hexavalentchromium.1.3 This test method measures hexavalent chromium usingan ion chromatographic separation combined with a postseparation reaction with a colorimetric reagent and photometricdetection.1.4 This test method is applicable in the range from 0.2 to100 ng/m3of hexavalent chromium in the atmosphere assum-ing 20 m3of air sample.The range can be extended upwards byappropriate dilution.1.5 The values stated in SI units are to be regarded as thestandard.The inch-pound units given in parentheses are forinformation only.1.6 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.2.Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheres3D 1357 Practice for Planning the Sampling of the AmbientAtmosphere3D 2914 Test Methods for Sulfur Dioxide Content of theAtmosphere(West-Gaeke Method)3D 3195 Practice for Rotameter Calibration3D 3586 Test Method for Chromium in Workplace Atmo-spheres(Colorimetric Method)43.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D 1356.3.2 Definitions of Terms Specific to This Standard:3.2.1 eluentthe ionic mobile phase used to transport thesample through the ion exchange column.3.2.2 resolutionthe ability of a column to separate con-stituents under specified test conditions.4.Summary of Test Method4.1 Sample Collection:4.1.1 Air is drawn at a rate of 15 L/min over a continuous24-h period through three 500-mL glass impingers(in-line)filled with 0.02 N sodium bicarbonate NaHCO3“buffer”solution.A target air volume of 20 m3is sampled.4.1.2 Impinger buffer solution has a pH of 8.2 and wasselected to prevent hexavalent chromium from being reducedto trivalent chromium Cr(III)in an acidic medium duringsampling(4).4.1.3 The impinger buffer solution from each impinger isanalyzed for hexavalent chromium.4.2 Sample Analysis(1,2,3,4)5:4.2.1 A volume of filtered sample,typically 1 mL,isinjected into the eluent flow path and separated by anionexchange using an ammonium sulfate(NH4)2SO4 basedeluent.4.2.2 After separation,the sample is reacted with an acidicsolution of diphenylcarbohydrazide.Hexavalent chromiumreacts selectively with this reagent to form the characteristicviolet colored complex.4.2.3 The eluent stream passes through a photometric de-tector for detection of the chromium diphenylcarbohydrazidecomplex by visible absorbance at 520 nm.Absorbance isproportional to the hexavalent chromium concentration.1This test method is under the jurisdiction of ASTM Committee D22 onSampling and Analysis of Atmospheres and is the direct responsibility of Subcom-mittee D22.03 on Ambient Atmospheres and Source Emissions.Current edition approved October 10,1998.Published December 1998.Origi-nally published as D 5281 92.Last previous edition D 5281 92(1997)e1.2Annual Book of ASTM Standards,Vol 11.01.3Annual Book of ASTM Standards,Vol 11.03.4Discontinued;See 1991 Annual Book of ASTM Standards,Vol 11.03.5The boldface numbers in parentheses refer to a list of references at the end ofthe text.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.Significance and Use5.1 Hexavalent chromium has been shown to be a humanrespiratory carcinogen in epidemiological studies when hu-mans are exposed to relatively high airborne concentrations.Such high exposures may also induce dermal sensitization tohexavalent chromium in humans(5).5.2 Ambient atmospheric concentrations of hexavalentchromium are well below detection limits of sampling methodsincluding Test Method D 3586 and NIOSH-7600(1).5.3 Objective assessment of ambient atmospheric concen-trations of hexavalent chromium provides a means of evaluat-ing exposures to atmospheric hexavalent chromium in amanner that can be related to health-based risk levels.Collect-ing such actual monitoring data reduces or