Decomposição de carbamazepina em sistema fechado por combustão iniciada por microondas para posterior determinação de Cd, Cu e Pb

Abstract

In this work, a decomposition procedure was proposed based on sample combustion assisted by microwave radiation. Samples of carbamazepine, a medicine used in the treatment of the epilepsy were used. The decomposition of samples were made using commercial quartz vessels, these are widely used in analytical routine for sample preparation. A quartz holder was adapted to the quartz vessels. After, the sample is positioned in the holder, this was inserted and stay suspended inside the quartz vessels on the top of vessel. The quartz holder, works as a protection for the cap of vessel from the flame produced by sample combustion. Three different sample preparation procedures for carbamazepine combustion: as pressed pellets, in cigarette paper capsules, in methyl cellulose capsules and as aqueous slurry with agar. A filter disk of paper was used as combustion auxiliary, it was positioned in the base of sample holder and an adequate volume of the ammonium nitrate solution was added as ignition starter. After the addition of absorber solution and the sample holder the vessels were closed, pressurized and inserted inside the microwave oven. Once started the microwave irradiation, the time necessary for the beginning of the combustion was about 4 s and the time for the combustion process was about 15 s for four test samples with about 250 mg. Different absorber solutions were evaluated for the analytes: H2O, HNO3 0,5 mol L-1, HNO3 1 mol L-1, HNO3 7 mol L-1 e HNO3 14 mol L-1. Different repose time after sample combustion were tested: 10, 20 e 30 min and also different reflux times, for dissolving the remained analytes adsorbed in the system after sample combustion (5, 10 e 15 min). For evaluation of the efficiency of the proposed procedure for carbamazepine decomposition after microwave-assisted combustion, spiked samples with Cd, Cu and Pb for further flame atomic absorption spectrometry determination was performed.