Determination of chromium species in environmental water and human serum samples by FAAS after magnetic solid phase extraction

Abstract

Silica-coated Fe3O4 magnetic nanoparticles (SCMNPs) modified with N-(2-aminoethyl)-3-aminopropyltrimethoxy-silane (AEAPS) (AEAPS-SCMNPs) were prepared and employed as magnetic solid phase extraction (MSPE) adsorbent for differentiation between Cr(III) and Cr(VI) in environmental water and human serum samples. At pH 5.0-9.0, AEAPS-SCMNPs were selective towards Cr(III) but hardly Cr(VI). The retained Cr(III) was subsequently eluted with 1.0 mL of 1.0 mol L-1 HNO3 followed by magnetic decantation. Total chromium was determined after reduction of Cr(VI) to Cr(III) by ascorbic acid. A speciation procedure for chromium in environmental water and human serum samples by AEAPS-SCMNPs-MSPE prior to FAAS analysis was developed. Various parameters affecting AEAPS-SCMNPs-MSPE were optimized systematically. Under the optimum conditions, the adsorption capacity of AEAPS-SCMNPs for Cr(III) was 22.6 mg g-1. With an enrichment factor of 100, a detection limit of 0.66 ng mL-1 Cr(III) was obtained, and the proposed method was successfully applied for the speciation of chromium in environmental water and human serum samples with satisfactory results.