Identification of impurities and statistical classification of methamphetamine hydrochloride drugs seized in China

A total of 48 methamphetamine hydrochloride samples from eight seizures were analyzed using gas chromatography–mass spectrometry (GC–MS) and gas chromatography with a flame ionization detector (GC–FID).Major impurities detected include 1,2-dimethyl-3-phenylaziridine, ephedrine/pseudoephedrine, 1,3-dimethyl-2-phenylnaphthalene, 1-benzyl-3-methylnaphthalene. These data are suggestive of ephedrine/pseudoephedrine as the main precursor of the methamphetamine hydrochloride samples seized during 2006–2007. Additionally the presence of 1,3-dimethyl-2-phenylnaphthalene, 1-benzyl-3-methylnaphthalene is indicative that six seizures were synthesized via the more specific ephedrine/hydriodic acid/red phosphorus method.In addition, five impurities were found for the first time in methamphetamine hydrochloride samples. Seventeen impurity peaks were selected from the GC–FID chromatograms. The peak areas of the selected peaks were then grouped for cluster analysis.