Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole ort hogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography, To t his end, the detection limits and linear dynamic range in particular were s tudied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine st andards and 3,4-methylenedioxyethylamphetamine for internal standardisation , In a second phase, the experiment was repeated with real biological extra cts (whole blood, serum, and vitreous humour), A calibration for 3,4-methyl enedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine wa s prepared in each of these matrices again using 3,4methylenedioxyethylamph etamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection f or the same extracts. The Q-TOP results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2)= 0.9998, 1/x weighting), Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably, It w as concluded that the Q-TOP achieves a linear dynamic range for quantitativ e LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright (C) 1999 John Wiley & Sons, Ltd.