Rapid on-line solid phase enrichment using polytetrafluoroethylene beads for chromium speciation in contaminated real water samples

Abstract

Due to unchecked disposal of industrial wastes into surrounding areas, the pollution of water bodies with heavy metal toxicants has become an environmental menace. The toxicity of chromium species depends on its oxidation states, and thus regular monitoring of environmental water sources vulnerable to pollution is a must. In this regard, an on-line method for chromium speciation and determination using FAAS has been proposed. The flow-injection preconcentration mini-column containing polytetrafluoroethylene beads was used as the solid phase extractant, and chromium speciation was done by complexing Cr(III) and Cr(VI) with thiosemicarbazide chelating agent. The figures of merit for Cr(III) and Cr(VI) obtained were 61 and 56 (preconcentration factors); 0.13 and 0.14 µg L−1 (detection limits); 1.6 and 1.3% (R.S.D.). The optimized method for chromium speciation was successfully applied to industrial and Yamuna River water samples. The method validation was carried out using SRM 1640a (Trace Elements in Natural Water, NIST), and recovery > 95% was obtained.