Facile and Sensitive Spectrophotometric Determination of Chromium

Abstract

A simple, sensitive, and selective spectrophotometric method is developed for the determination of trace amounts of chromium(VI) in various samples. The method is based on oxidation of 2,4-dinitrophenylhydrazine (DNPH) by chromium in an acidic medium and coupling with β-naphthol to give a red-colored dye, having an absorbance maximum at 663 nm, and/or coupling with α-naphthol to give a violet-colored dye, having an absorbance maximum at 503 nm. The method obeys Beer's law in the concentration range 0.02–4.0µg mL−1 and 0.05–9.0 µg mL−1, respectively. The optimum reaction conditions and other important analytical parameters were established. Interference caused by various nontarget ions was also investigated. The proposed method is applied to the analysis of chromium(VI) in environmental, pharmaceutical, and steel samples. The performance of the proposed method is evaluated using the student's t and F -tests.