Separation/preconcentration of chromium species with continuous liquid-liquid extraction device and its determination by AAS

Abstract

A chromium speciation and preconcentration method was developed for graphite furnace atomic absorption spectrometry (GFAAS). This method was based on a continuous liquid-liquid extraction technique. For the separation and enrichment of the chromium species, an ion-pair forming quaternary ammonium compound was used. The sample and chloroform with the ion-pair forming agent were introduced into a patented extraction glass device. After the extraction, the Cr(VI) content of real water samples was determined by GFAAS. The optimized extraction conditions were as follows: the detection limit (S/N = 3) of 0.01 μg L−1, linear range of 0.04–5.00 μg L−1 and precision (RSD, n = 3) ≤ 3.0%. The advantages of this method are its simplicity, cost efficiency, the high enrichment factor of chromium species and easy usage with the GFAAS technique. Thus, the concentration of the chromium species can be determined at sub μg L−1 level.