Chemical Speciation of Arsenic and Chromium in Seafood by LC-ICP-MS

Two methods were developed for the As and Cr species determination in different kinds of seafood, exploring the LC-ICP-MS potential and chemometric approach to define the extraction conditions. Adequates separation and sensitivity data by LC-ICP-MS were obtained with 0.01 mol L-1 (NH4)2HPO4 in 1% ethanol (pH 8.0) for arsenic, and 0.015 mol L-1 Na2SO4, 0.005 mol L-1 EDTA, and 0.005 mol L-1 NaH2PO4 (pH 7.0) for chromium. The Doehlert matrix and Box-Behnken design defined the ideal extraction conditions for arsenic and chromium species. For As extraction, the optimized conditions employed 0.1 g of sample and 30 mmol L-1 HNO3 at 90°C for 45 min, and Cr, 0.1 g of sample and 0.045 mol L-1 [EDTA] at 90°C for 40 min. Recoveries from 88 to 106% of arsenobetaine (AsB), arsenite [As(III)], dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenate [As(V)], Cr(III) and Cr(VI) were obtained for all evaluated samples. The limits of quantification provided by the proposed methods were 5.3; 52.1; 16.4; 2.8; 83.3; 113.8; 53.9 ng g-1 for AsB, As(III), DMA, MMA, As(V), Cr(III) and Cr(VI) respectively. The trueness was evaluated using certified reference materials and addition and recovery procedures. The sum of the species agreed with the total concentration of arsenic and chromium contents.