Utilization of 2-Amino-6-(1,3-thiazol-2yldiazenyl)phenol for Chromium Speciation in Environmental Samples

Abstract: Due to the toxicity of chromium, species depend on their chemical properties and bioavailabilities, speciation of chromium are very important in environmental samples. A speciation procedure for chromium(III), chromium (VI) and total chromium in environmental samples is presented in this work, prior to Cr(III) complexation with new reagent 2-amino-6-(1,3-thiazol-2- yldiazenyl)phenol (ATDP) at the optimum conditions and measured spectrophotometrically. After reduction of Cr(VI) by 0.05 M sodium sulfite, the system was applied to the total chromium. Cr(VI) was calculated as the difference between the total Cr content and the Cr(III) concentration. The influences of the analytical parameters including pH of the aqueous solution and its amounts, reagent concentration, time and temperature were investigated. The complex gives a maximum absorption at 503 nm with a molar absorptivity coefficient of 1.04 × 106 L mol−1 cm−1. The linear range for Cr(III) determination is 10–400 ng/mL. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in environmental samples including natural waters and total chromium in digested tobacco, coffee, tea, and soil samples, comparing the results simultaneously with those obtained using an atomic absorptio