An environment-Friendly Cloud Point Extraction Method for preconcentration and determination of Lead and Cadmium in Water Samples

Abstract

A new, cost-effective, and environmental-friendly cloud point extraction methodology was described for enrichment of lead and cadmium in real water samples. The method involves the complexation of lead or cadmium with 2-nitro-6-(1,3-thiazol-2-diazeyl)-phenol at pH 8.5 and 7.0 for cadmium and lead, respectively, then extraction into Triton X-114. After dilution of the surfactant-rich phase with acidified methanol, the enriched analytes concentration was estimated by spectrophtotmetric measurements at 590 and 540, respectively. Parameters that influenced cloud point extraction, such as pH, reagent, surfactant and nitric acid concentrations, centrifuge rate and time, temperature, incubation time, as well as interferences were evaluated and optimized. The preconcentration factor was 50 and the detection limits were 1.64 and 1.62 µg L-1 for lead and cadmium, respectively. The method presented relative standard deviation as precision were 2.28% and 1.96% for lead and cadmium, respectively. The accuracy of the new preconcentration procedure was checked by the analysis of the standard reference materials, and successfully applied to determine lead and cadmium in real water samples with relative recovery values in the range of 95.40%–101% for the spiked samples.