Measurement of Chromium Species in Water Samples

Abstract

While trivalent chromium (Cr(III)) is an essential nutrient, hexavalent chromium (Cr(VI)) is a human carcinogen and genotoxic. In evaluation of the toxicological risks and environmental impacts, the separate analysis of Cr(III) and Cr(VI) in water samples provides more information than the analysis of total Cr. The relatively high instability of the Cr species in natural water samples further complicates the analysis, requiring preservation or other advanced procedures. This article is intended to present the broad range of available separation methods for Cr analysis, discussing the possible interferences, detection limits, and preserving options. The intense color complex formed between dichromate ions and 1,5‐diphenylcarbazide (DPC) is used for Cr(VI) measurement in spectrophotometric, flow injection analysis (FIA), ion chromatography (IC), liquid chromatography (LC), capillary electrophoresis (CE), and electrochemical methods. Atomic spectrometry, molecular spectrometry, and other methods are also discussed. An absolute analysis with accurate measurement of Cr(VI) at the time of sample collection can be achieved with speciated isotope dilution mass spectrometry (SIDMS) by using LC separation coupled to the inductively coupled plasma mass spectrometry (ICP‐MS) or IC separation coupled to electrospray ionization tandem mass spectrometry (ESI‐MS/MS).