Reduction of hexavalent chromium in water samples acidified for preservation

Journal of Environmental Quality
By:  and 



Reduction of hexavalent chromium, Cr(VI), in water samples, preserved by standard techniques, was investigated. The standard preservation technique for water samples that are to be analyzed for Cr(VI) consists of filtration through a 0.45‐µm membrane, acidification to a pH < 2, and storage in plastic bottles. Batch experiments were conducted to evaluate the effect of H+ concentration, NO2, temperature, and dissolved organic carbon (DOC) on the reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) to Cr(III) increased with increasing NO2, DOC, H+, and temperature. Reduction of Cr(VI) by organic matter occurred in some samples even though the samples were unacidified. Reduction of Cr(VI) is inhibited to an extent by storing the sample at 4°C. Stability of Cr(VI) in water is variable and depends on the other constituents present in the sample. Water samples collected for the determination of Cr(VI) should be filtered (0.45‐µm membrane), refrigerated, and analyzed as quickly as possible. Water samples should not be acidified. Measurement of total Cr in addition to Cr(VI) can serve as a check for Cr(VI) reduction. If total Cr is greater than Cr(VI), the possibility that Cr(VI) reduction has occurred needs to be considered.

Publication type Article
Publication Subtype Journal Article
Title Reduction of hexavalent chromium in water samples acidified for preservation
Series title Journal of Environmental Quality
DOI 10.2134/jeq1985.00472425001400030017x
Volume 14
Issue 3
Year Published 1985
Language English
Publisher Wiley
Contributing office(s) Toxic Substances Hydrology Program
Description 4 p.
First page 396
Last page 399
Google Analytic Metrics Metrics page
Additional publication details