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Simultaneous determination of cocaine, opiates and amphetamines in serum by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) allowed to replace favourably gas chromatography coupled to mass spectrometry (GC-MS) used until now in our laboratory. It had to answer to accreditation demand according to Belgian Accreditation (Be lac).

Twenty-one deutereted internal standards were added to 500 mu L of serum. Sample pre-treatment consisted of solid-phase extraction using Oasis MCX cartridges 1mL, 30mg (Waters, Zellik, Belgium). Chromatographic separation was done on an Acquity HSS T3 column (2.1 x 100mm, 1.8 mu m, Waters). Mobile phase consisted of pH 3 ammonium formate buffer and of methanol adjusted to pH 3 with formic acid. Compounds were next analysed by tandem mass spectrometry operated in the multiple reaction monitoring (MRM) mode. The method was validated using total error approach.

Twenty-seven drugs were separated in 19 minutes. The linearity of the method was acceptable in the validated range of concentrations. The bias and the relative standard deviations for repeatability and intermediate precision were acceptable. Lower and upper beta-expectation tolerance limits did not exceed the acceptance limits of 20% for concentrations upper than 20 mu g/L and 50% for concentrations lower than 20 mu g/L. The limits of quantitation were tower than 7 mu g/L for all compounds.