Preconcentration and Determination of Zinc and Lead Ions by a Combination of Cloud Point Extraction and Flame Atomic Absorption Spectrometry

The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead(II) and zinc(II). After complexation with 3-[(4-bromophenyl) (1-H-inden-3-yl)methyl]-1 H-indene (BPIMI), the analytes were quantitatively extracted to a phase rich in Triton X-114 after centrifugation. Methanol acidified with 1 mol/L HNO3 was added to the surfactant rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of bis((1H-benzo [d] imidazol-2y)ethyl)sulfane, Triton X-114, pH and amount of surfactant were all optimized. Detection limits (3 SDb/m) of 2.5 and 1.6 ng/mL for Pb2+ and Zn2+ along with preconcentration factors of 30 and an enrichment factor of 32 and 48 for Pb2+ and Zn2+ ions were obtained, respectively. The proposed cloud point extraction was been successfully applied for the determination of these ions in real samples with complicated matrices such as food and soil samples, with high efficiency.