Preconcentration and separation of ultra-trace amounts of lead using ultrasound-assisted cloud point-micro solid phase extraction based on amine functionalized silica aerogel nanoadsorbent

A new method based on ultrasound-assisted cloud point-micro solid phase extraction (USA-CP-MSPE) with amine functionalized silica aerogel (AFSA) was used for separation and preconcentration of Pb(II) ions in water samples. At optimized pH, the mixture of AFSA and Triton X-100 as a nanoadsorbent and nonionic surfactant, respectively, was added to the aliquot of lead standard solution. Then, the sample was transferred to an ultrasound bath and placed in a thermostat water bath, and cooled in an ice-bath. In this step, the nanoadsorbent easily settled down in the surfactant phase and the enriched surfactant phase was separated from the aerogel nanoadsorbent by centrifugation. The analyte was back-extracted from nanoadsorbent with nitric acid solution (1.0 M) and its concentration was determined by electrothermal atomic absorption spectrometry (ETAAS). Under the optimized conditions, the linear range was 0.04-1.45 μg L− 1 for Pb(II) and the limit of detection was evaluated as 0.01 μg L− 1 (peak area). An enrichment factor of 102 was achieved. Afterwards, the optimized method was applied to the determination of lead in real water samples that includes sea, river, tap and rain water.