Determinação de cocaína e lidocaína em saliva empregando preparo de amostra assistido por campo elétrico associado à cromatografia líquida-espectrometria de massas sequencial

Abstract

Drug use is a worldwide problem and public health in Brazil. Among the drugs consumed cocaine stands out for its wide distribution, use and easy to obtain. Usually several adulterants are found with cocaine to increase the volume and to reduce the costs and one of them is thedrug lidocaine. In order to attest to the consumption of drugs, it is necessary to determine it in some biological fluid or tissue and therefore, the development of increasingly sensitive analytical methods is necessary. In this way, the sample preparation becomes anindispensable step to reduce the interferents and to preconcentrate the analytes. In this work, a sample preparation technique was developed that consists of a three-phase extraction (liquid-liquid-liquid supported solid) assisted by electric fields to determine cocaine andlidocaine in artificial saliva with subsequent determination by liquid chromatography coupled to sequential mass spectrometry. In order to carry out multiple simultaneous extractions, a simple, inexpensive and efficient device with multi-wells was created, which allows the extraction of 66 samples in a practical and reproducible way. Firstly, a univariateoptimization was performed for the extraction parameters as the acceptor phase, the pH of the sample and the acceptor phase, and the percentage of the water miscible solvent added to the organic filter. The best conditions for these parameters were 400 mmol L-1 acetic acidsolution at pH 3.0 as the acceptor phase and organic filter consisting of 1-octanol: methanol (90:10) v / v. Then, a Doehlert-type experimental design was performed to draw a response surface in terms of desirability, of the parameters ofextraction electric potential andextraction time, where the values of 300 V and 30 min were obtained.