On-site determination of arsenic in soil extract by anodic stripping voltammetry with gold film electrode after solid phase pretreatment

A method for the on-site estimation of arsenic (As) contamination in soil by solid-phase extraction with a resin based on molecular recognition technology (SPE-MRT) and anodic stripping voltammetry (ASV) using a gold film microelectrode was developed. Optimized pretreatments were carried out as follows: I g of soil sample was taken and put into polypropylene test tube containing 33 mL 1 M hydrochloric acid solution, which was heated at 70 degree Celsius for 5 min using graphite block hot plate. As in the sample was extracted by shaking for I min using an automatic mini-shaker system. The extract was finally filtered through a 0.45 mu m disk PTFE membrane filter. The extracted arsenic was electrodeposited on the gold film carbon microelectrode at -400 mV vs. Ag/AgCl for 1 min and the deposits were stripped at a rate of 5 mV/s to 580 mV vs. Ag/AgCl by using AnaLigo (R) TE-3, Cu in soil extract was removed with 1 M hydrochloric acid for the determination of As. The method can eliminate Cu interference. The detection limit was 0.5 mu g/L in soil extract. The results of voltammograms for As in the extracts from real soil samples were the same level as these obtained by a cross-check method using inductively coupled plasma mass spectroscopy (ICP-MS).