Nano-alumina coated with SDS and modified with salicylaldehyde-5-sulfonate for extraction of heavy metals and their determination by anodic stripping voltammetry

A green and highly selective solid phase extraction was employed for simultaneous preconcentration and determination of lead and zinc ions in complex real samples by differential pulse anodic stripping voltammetry. The presented method is based on the adsorption of zinc and lead ions on SDS-coated nano-alumina modified with sodium salicylaldehyde-5-sulfonate (SAS). The influence of effective parameters on the separation and preconcentration of the analytes, such as amount of adsorbent, pH and flow rate of sample, volume and concentration of eluent, and effect of possible matrix ions was investigated. Under the best conditions (eluent: HNO3, 3.0 mL, 3.0 mol L−1; adsorbent: 0.7 g of nano-alumina, 30 mg of SDS, 9.4 mg of SAS; and sample: pH 5), adsorption capacity, enrichment factors, and limits of detection for metal ions were 7.8–8.5 mg g−1, 83–167 and 0.0046–0.026 μg L−1, respectively. Calibration graphs were linear in the range of 0.01–100 and 0.08–150 μg L−1 for Pb (II) and Zn (II), respectively. At the end, the proposed method was successfully applied for determination of the analytes in tap water and different food samples such as rice seed, apple juice, coriander and lettuce.