Profiling of impurities in illicit methamphetamine by high-performance liquid chromatography and capillary electrochromatography

High performance liquid chromatography (HPLC) with photodiode array (PDA) U V and fluorescence (FL) detection, and capillary electrochromatography (CEC ) with laser-induced fluorescence (LIF) detection were investigated for the analysis of acidic extracts derived from illicit methamphetamine. These co mpounds include major impurities from the hydriodic acid/red phosphorous re duction method, i.e., 1,3-dimethyl-2-phenylnaphthalene and 1-benzyl-3-methy lnaphthalene, and other trace-level, structurally related impurities. For c ertain of these solutes, HPLC with conventional FL detection gave at least a 60x increase in sensitivity over UV detection. In addition, other highly fluorescent impurities were detected in methamphetamine produced via four o ther synthetic routes. The use of a rapid scanning FL detector (with acquis ition of "on the fly" excitation or emission) provided structural informati on and gave "optimum" excitation and emission detection wavelengths. CEC wi th LIF detection using UV laser excitation provided greatly improved chroma tography over HPLC, with good detection limits in the low ng/ml range. Both methodologies provide good run-to-run repeatability, and have the capabili ty to distinguish between samples. (C) 2000 Published by Elsevier Science B .V.