Seized methamphetamine samples with unique profiles of stable nitrogen isotopic composition documented by stable isotope ratio mass spectrometry

摘要

We report a case of seized methamphetamine (MA) samples showing unique profiles of stable isotopic compositions. Three packages of MA-HCl samples seized simultaneously from one suspect were subjected to gas chromatographic impurity profiling and stable isotope ratio mass spectrometry (IRMS). The samples showed similar impurity profiles by gas chromatography, but their stable isotopic compositions were complicated. The δ15N values of the samples from each package varied widely when the crystals were analyzed separately; we could differentiate two major groups labeled I and II, and also their subgroups. Each of the three packages contained MA-HCl crystals belonging to multiple groups and subgroups. It was considered that several batches of MA-HCl with starting materials from different sources were mixed together after a similar or the same synthesis procedure and then divided into the packages. This is the first report to show that stable IRMS is useful for differentiating seized MA using small crystals from different sources.