Determinação de Cd e Pb por espectrometria de absorção atômica em suplementos alimentares oleosos após extração por quebra de emulsão

Abstract

Food supplements are obtained synthetically and derived from plants, and metal contamination may occur due to the industrial environment, soil geochemical characteristics, among other forms. In this work, a method for the determination of cadmium (Cd) and lead (Pb) in oily food supplements is described using emulsion breakage-induced extraction (EIEB) and continuous source high resolution atomic absorption spectrometry equipped with a graphite furnace. (HR CS GFAAS). The sample preparation method is based on the formation of a water/oil emulsion by adding an extractor solution composed of 5% Triton X-100 and 15% hydrochloric acid (HCl) to the oil sample diluted with 1.5 mL of toluene and break this emulsion by centrifugation (4000 rpm for 5 minutes). Two well-defined phases were formed and the acidic aqueous phase containing the extracted Cd and Pb ions was analyzed by HR CS GFAAS. Different parameters that influence the extraction efficiency of Cd and Pb were univariately optimized. A matrixbased calibration method was applied to compensate for interference caused by matrix effects. Precision, expressed as relative standard deviation, was less than 11% for Pb and less than 7% for Cd. The detection limits were 3.32 µg/Kg for Pb and 1.51 µg/Kg Cd. The accuracy of the methods was evaluated by means of analyte addition and recovery tests using the safflower oil supplement sample prepared by the emulsion procedure, and the values obtained showed a confidence interval between 94.65-108.41% with Pb and 100.8-106.1% with Cd. The performance parameters of the methods were in accordance with the American Pharmacopoeia standards for inorganic analysis in food supplements. The amount of lead and cadmium were determined in 9 oily food supplements available in the Brazilian market. The Cd concentration ranged from 8.81 to 9.35 µg/Kg and the highest Pb concentration was 19.91 µg/Kg. The proposed sample preparation by breaking emulsions of oily dietary supplements proved to be a simple and efficient strategy to assess the quality of oily supplements in terms of Pb and Cd concentration determined by HR CS GFAAS.