Applicability of ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry for cocaine profiling.

Abstract

For the first time in China, the chemical profiling of cocaine specimens was performed at the National Narcotics Laboratory. An ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-QTOF-MS) method was developed and validated for simultaneous analysis of 14 cocaine alkaloids and 5 main adulterants. Among them, ecgonine methyl ester, ecgonine, benzoylecgonine, and norcocaine were identified by comparing with the standard materials; tropacocaine, 3,4,5-trimethoxycocaine, cis-/trans-cinnamoylcocaine were tentatively identified based on the exact masses of protonated molecules and product ions; six unidentified alkaloids of 182/1.47, 316/9.54, 659/9.85, 316/9.87, 420/10.34, and 420/10.85 were marked with 'extracted mass/retention time' for convenience. Minimum sample preparation and analysis time were required, which was suitable for routine analysis. Based on the semi-quantitative data set of 14 alkaloid impurities in 131 linked/unlinked cocaine samples, 50 combinations of pretreatment methods and distance/correlation measurements were tested for their potential discrimination power for cocaine profiling, and Logarithm/Pearson exhibited the best result. After hierarchical cluster analysis (HCA), 183 cocaine samples collected from 2011 to 2015 were classified into 7 major groups. Moreover, 37 groups of linked samples were found within and between provinces, which provide intelligence for the case connection and revealing of the distribution networks. Our results highlighted the practical utilities of drug profiling, especially to support the investigation through operational intelligence and to improve the knowledge related to the drug trafficking through strategic intelligence. Copyright © 2016 John Wiley & Sons, Ltd.