ABSTRACT
In this study, stable isotope ratio analysis was used to track the precursor information of methamphetamine. The δ13 C and δ15 N values of 30 nature ephedra plants, 12 synthetic ephedrine/pseudoephedrine (ephedrine), 14 natural ephedrine, and 987 seized methamphetamine samples were measured and compared. Due to different weather and earth conditions, the δ13 C and δ15 N values of ephedra plants grown in the east and the west of Inner Mongolia showed great difference. The δ15 N values of ephedra plants were consistent with related ephedrine extracted from them. Moreover, the criteria to infer the synthetic origin of ephedrine were set up after the analysis of natural and synthetic ephedrine samples. Finally, the precursor origins of 949 seized methamphetamine samples synthesized by Emde and Nagai method were tentatively inferred. Influenced by different preprecursors, the δ13 C values of seized methamphetamine samples that synthesized from P2P also showed great difference, and this result is consistent with the reported data.