title: Field method for the determination of insoluble or total hexavalent chromium in workplace air.
abstract: National Institute for Occupational Safety and Health method 7703 is a portable field procedure for the analysis of workplace air filter samples for hexavalent chromium (CrVI) content immediately after the samples are collected. The field method prescribes CrVI extraction from air filter samples with an ammonium sulfate/ammonium hydroxide extraction buffer using ultrasonic extraction (UE). Strong anion-exchange solid-phase extraction (SAE-SPE) is then used to separate CrVI from trivalent chromium and other interferences. Portable spectrophotometric measurement of CrVI is then conducted using the 1,5-diphenylcarbazide (DPC) method. However, it has been found that the ammonium extraction buffer does not adequately bring insoluble CrVI compounds into solution during the UE process. Thus, it was deemed necessary to modify the field method so that it would provide acceptable recoveries for insoluble CrVI compounds. To this end, a more alkaline extraction solution--sodium carbonate/sodium bicarbonate buffer--was investigated. The modified procedure using the highly alkaline extraction solution was demonstrated to be compatible with SAE-SPE cartridges when determining insoluble CrVI in air filter samples. It was found that the carbonate/bicarbonate buffer was equally effective for complete dissolution of both insoluble and soluble forms of CrVI. Furthermore, the modified procedure met desired performance criteria established for air sampling and analytical methods.
authors.affiliation: US Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Spokane, Washington 99207, USA.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Hazelwood
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Drake
authors.forename: Kevin
authors.initials: K
authors.lastname: Ashley
authors.forename: Dale
authors.initials: D
authors.lastname: Marcy
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D002021:Buffers; D002274:Carcinogens, Environmental / Q000032:analysis*; D002857:Chromium / Q000032:analysis*; D004784:Environmental Monitoring / Q000592:standards; D005374:Filtration; D006801:Humans; D009314:National Institute for Occupational Safety and Health, U.S.; D016273:Occupational Exposure; D012680:Sensitivity and Specificity; D012995:Solubility; D014481:United States; D017132:Workplace
chemical_list: D002021:Buffers; D002274:Carcinogens, Environmental; D002857:Chromium; C074702:chromium hexavalent ion