Chemically Modified Polymeric Solid Support for Chromium(III) Speciation in Industrially Polluted Water Samples and Determination by FI-FAAS

The rampant dumping of industrial effluents rich in chromium has increased pollution in the natural water bodies. The contrasting bio-toxicity of its two most stable forms, Cr(III) and Cr(VI), make it essential that they be separated and accurately determined by FI-FAAS when present together. A new chemically modified polymeric solid support, Dowex Optipore L493 functionalized with (x-picolinic acid, was used for the selective preconcentration of Cr(III), while Cr(VI) was determined by reduction to Cr(III). Singular analytical techniques suffer from low sensitivity and are unable to differentiate between the bio-essential Cr(III) and carcinogenic Cr(VI) states. Thus, the on-line preconcentration method aims to improve matrix elimination, enhance trace chromium detection limits, and provides faster sampling. The factors influencing Grail) preconcentration were optimized for maximum recovery. The chromium preconcentration efficiency in the presence of several matrix ions was studied. For a 100-second preconcentration time, a preconcentration factor of 78 and detection limit of 0.14 mu g L-1 were obtained. The RSD (n = 5) was 1.3%. The linearity of the determinations was up to 540 mu g L-1. Spike recovery studies in real water samples were performed using standard NIST Cr(III) and Cr(VI) solutions, and a recovery of >95% was obtained. The proposed method was validated using NIST SRM 1640a Trace Elements in Natural Water.