15N/14N isotopic ratio and statistical analysis: an efficient way of linking seized Ecstasy tablets

In this study, the 15N/14N isotopic ratios of 106 samples of 3,4-methylenedioxymethamphetamine (MDMA) extracted from Ecstasy tablets are presented. These ratios, measured using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), show a large discrimination between samples with a range of (delta)^15N values between -17 and +19‰, depending on the precursors and the method used in clandestine laboratories. Thus, (delta)^15N values can be used in a statistical analysis carried out in order to link Ecstasy tablets prepared with the same precursors and synthetic pathway. The similarity index obtained after principal component analysis and hierarchical cluster analysis appears to be an efficient way to group tablets seized in different places.