Determinação de As, Cd, Hg E Pb em mel empregando combustão iniciada por micro-ondas e ICP-MS

Abstract

In this work, a microwave-induced combustion (MIC) method was proposed for the decomposition of honey, aiming at As, Cd, Hg and Pb determination by ICP-MS. Parameters such as sample mass (with or without the use of combustion aids), composition and concentration of the absorbing solution and microwave oven irradiation program were evaluated. Mass of 0.8 g of honey (with 0.4 g of microcrystalline cellulose and 100 μL of 6 mol L-1 NH4NO3) was decomposed by MIC, using 6 mL of 1 mol L-1 HNO3 as absorbing solution. The digests presented carbon concentration below 25 mg L-1, allowing the determination by ICP-MS free of interference caused by carbon compounds. The accuracy of the proposed method was evaluated based on recovery tests using standard addition and by comparison using microwave-assisted wet digestion with single reaction chamber (MAWD-SRC). The proposed method allowed recoveries between 99 and 104% for the studied analytes and did not show any significant difference in comparison to the results obtained by MAWD-SRC. The LOD values obtained using the optimized conditions were 1.10, 1.70, 2.90 and 4.60 ng g-1 for As, Cd, Hg and Pb, respectively. In this way, it was possible to develop a suitable method for the decomposition of honey and subsequent determination of these elements in order to meet the current legislation, using diluted reagents. The proposed method was also applied to honey samples from different geographical origins, which presented varying concentrations of analytes.