A cloud point extraction procedure for preconcentration/flame atomic absorption spectrometric determination of silver, zinc, and lead at subtrace levels in environmental samples.

A cloud point extraction (CPE) procedure was presented for the preconcentration of silver, zinc, and lead ions in various samples. The complexes of these metal ions with 2-(((1H-benzo[d]imidazol-2-yl)methoxy)methyl)-1H-benzo[d]imidazole (BIMMBI) are quantitatively extracted into the Triton X-114-rich phase after centrifugation. A solution of 1.0 M HNO3 in methanol was added to the surfactant-rich phase as the effective eluant before analysis by flame atomic absorption spectrometry. The influence of effective parameters such as the concentrations of BIMMBI, Triton X-114, and HNO3, pH, bath temperature, centrifuge rate, and time on method sensitivity and efficiency was optimized. Detection limits of 2.8, 1.7, and 1.1 ng/mL for Pb2+, Ag+, and Zn2+, respectively, along with a preconcentration factor of 30 and enrichment factors of 33, 48, and 53 for Pb2+, Ag+, and Zn2+, respectively, were obtained. The present CPE method is suitable for accurate and precise determination of trace amounts of analyte ions in complex matrixes. The proposed CPE procedure was applied to the determination of these ions in biological, natural water, wastewater, soil, and blood samples.