Determination of new pyrrolidino cathinone derivatives, PVT, F-PVP, MPHP, PV8, PV9 and F-PV9, in human blood by MALDI-Q-TOF mass spectrometry

Abstract

A rapid and sensitive detection method using matrix-assisted laser desorption ionization (MALDI)–quadrupole time-of-flight–mass spectrometry (Q-TOF–MS) was developed for the analysis of six pyrrolidino cathinone derivatives, α-pyrrolidinopentiothiophenone (PVT), 4′-fluoro-α-pyrrolidinopentiophenone (F-PVP), 4′-methyl-α-pyrrolidinohexanophenone (MPHP), α-pyrrolidinoheptanophenone (PV8), α-pyrrolidinooctanophenone (PV9) and 4′-fluoro-α-pyrrolidinooctanophenone (F-PV9), that were newly designated as illegal drugs in Japan. In this method, α-cyano-4-hydroxycinnamic acid was used as the matrix to assist the ionization of cathinones. MS spectra of these cathinones showed a protonated molecule [M+H]⁺ and iminium, respectively, and hence the main ions of MALDI–MS were a mixture of the main ions detected by liquid chromatography–electrospray ionization–mass spectrometry and that by gas chromatography–electron ionization–mass spectrometry. The quantification of these cathinones was performed using α-pyrrolidinopentiophenone as the internal standard. The limit of detection was 1 ng/ml and the quantification range was 2–100 ng/ml for these cathinones using 20 μl of blood. We encountered a fatal poisoning case where PV9 was abused. The PV9 levels in postmortem blood samples from the right heart, left heart and femoral vein were 198, 209 and 163 ng/ml, respectively. The metabolites of PV9 were detected, and the peak height of an oxidized metabolite was higher than those of the protonated molecule and the other metabolites.