DEVELOPMENT OF A NEW LIQUID PHASE MICROEXTRACTION METHOD FOR THE DETERMINATION OF SEVERAL ILLICIT DRUGS AND NPS IN ORAL FLUID BY HPLC-MS/MS ANALYSIS

Over the past decade, there has been a diversification of the substances available on the drug markets. In addition to traditional plant-based substances – cannabis, cocaine and heroin – the past decade has shown the expansion of a dynamic market both for new synthetic psycoative drugs and the non-medical use of pharmaceutical drugs or even prescription medicines. The availability of more potent drugs, the increasing number of substances and their consecutive or sequential use among occasional or regular users, poses a great challenge to the prevention of drug use and the treatment of drug use disorders1 . For these reasons, innovative methodologies to isolate and identify these molecules are of great interest. The aim of this work was the development of a new liquid phase microextraction method for the determination of several illicit drugs belonging to different pharmacological classes in oral fluid (OF) samples. The workflow is very simple: the sample was collected through passive drool and centrifuged; then, it was processed by parallel artificial liquid membrane extraction (PALME) and analysed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for the simultaneous identification and quantification of the selected analytes. PALME is an interesting liquid phase microextraction based on the use of a liquid support membrane which was first described and used in 2013 by Gjelstad et al2 . Using this technique, it is possible to extract, from an aqueous biological sample, acid, basic or neutral molecules by creating a suitabile pH gradient that facilitates the mass transfer of uncharged analytes across the liquid membrane with organic support3 . An experimental design approach has been applied for the identification of the operating conditions of each parameter that influences the extraction (extraction time, extraction pH, composition of the extracting solvent and acceptor solution, salt amount), and represented the best compromise for all analytes considered. The presented method proved to be suitable for analytes of different classes by using very small amounts of both organic solvents and biological samples, and so demonstrating to be an example of green chemistry. The method was subsequently validated following the guidelines of Scientific Working Group for Forensic Toxicology by evaluating parameters such as precision and accuracy, LOD and LOQ, linear dynamic range, matrix effect, recoveries.