Microextracao Induzida por Quebra de Emulsao (MIQE): Uma Opcao Pratica para o Preparo de Amostras de Oleo Diesel em Determinacoes de Cu, Ni e Pb por Espectrometria de Absorcao Atomica com Forno de Grafite

This work presents the development of a sample preparation method by microextraction induced by emulsion break (MIEB) for determination of Cu, Ni and Pb in diesel oils by graphite furnace atomic absorption spectrometry (GF AAS). In this case, the graphite furnace temperature program was optimized and the microextraction process was evaluated through the influence of the extractive phase volume; the type of acid used; the nitric acid concentration; and the surfactant Triton X-114 concentration. The best conditions were: 1.5 mL of diesel oil, 300 mu L of extractive solution composed of 2.5 % (w/v) Triton X-114 and 7.0 mol L-1 nitric acid. The emulsion was obtained after vigorous manual agitation of the mixture and broken in a water bath at 80 degrees C for 10 min. In this proposed method, MIEB was applied in five commercial samples of diesel oils for determination of Cu, Ni and Pb by GF AAS, presenting good performance when compared to the determinations made by inductively coupled plasma mass spectrometry (ICP-MS), besides consuming small amounts of sample and reagents and allowing the pre-concentration of the analytes.