Determination of added chromium(III) and chromium(VI) in natural water by ion-pairing high-performance liquid chromatography with detection by atomic absorption spectrometry

Abstract

A simple, rapid and selective method for the determination of Cr^III and Cr^VI in natural waters by ion-pairing high-performance liquid chromatography (HPLC) with flame atomic absorption spectrometry (FAAS) as the method of detection is described. The samples and standards are acidified with glacial acetic acid to a pH of 3.1–3.2. The eluent consists of dilute tetrabutylammonium phosphate also acidified to a pH of 3.1–3.2. Separation is accomplished on a 4 cm long column packed with polymeric C₁₈ material. The effluent from the column is fed directly into the atomic absorption spectrometer. Chromium(VI) added to pond water began to decay to Cr^III immediately upon addition. The rate of decay depended on the level of suspended organic material in the water. The recovery of the sum of both Cr^III and Cr^VI species in 65 spiked water samples was 100.9% with a standard deviation of 6.2%.