Two-Dimensional Gas Chromatography/Electron-Impact Mass Spectrometry with Cryofocusing for Simultaneous Quantification of MDMA, MDA, HMMA, HMA, and MDEA in Human Plasma

A two-dimensional gas chromatography–mass spectrometry method with cryofocusing simultaneously quantifies MDMA, its metabolites MDA, HMMA, and HMA, and MDEA in human plasma. Limits of quantification were 1.0 μg/L for MDA and 2.5 μg/L for the other four compounds. Calibration curves were linear up to 100 μg/L for MDA and HMA and up to 400 μg/L for MDEA, MDMA, and HMMA, with correlation coefficients above 0.997. Extraction efficiencies from plasma were at least 85%, recoveries ranged from 85.6% to 107.2% of target, and intra- and interassay imprecision was below 8.5% at three concentrations. None of 66 tested exogenous compounds interfered. The assay achieves low quantification limits suitable for pharmacokinetic studies and may apply to other analytes and complex matrices.

Study at a glance

Abstract

Abstract Background: 3,4-Methylenedioxymethamphetamine (MDMA, or Ecstasy) is a popular recreational drug. Analysis of MDMA and metabolites in human plasma, particularly in pharmacokinetic studies, requires low limits of quantification. Two-dimensional GC/MS with cryofocusing is a chromatographic technique recognized for its increased selectivity and resolution. Methods: This method simultaneously quantifies 3,4-methylenedioxyethylamphetamine (MDEA), MDMA, and its metabolites, 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), and 4-hydroxy-3-methoxyamphetamine (HMA) in human plasma. With hydrochloric acid, we hydrolyzed 1 mL plasma, fortified with internal standard. Analytes were subjected to solid-phase extraction, derivatized with heptafluorobutyric acid anhydride, and quantified using cryofocused 2-dimensional GC/MS operated in electron-impact selected ion-monitoring mode. Results: Limits of quantification were 1.0 μg/L for MDA and 2.5 μg/L for MDEA, MDMA, HMMA, and HMA. Calibration curves were linear to 100 μg/L for MDA and HMA and to 400 μg/L for MDEA, MDMA, and HMMA, with r2 > 0.997. At 3 concentrations spanning the linear dynamic range of the assay, mean overall extraction efficiencies from plasma were ≥85% for all compounds of interest. Recoveries were 85.6% to 107.2% of target, and intra- and interassay imprecision (CV) was <8.5% for all drugs at 3 concentrations within the range of the assay. None of the 66 exogenous compounds tested interfered with analyte quantification. Conclusions: This GC/MS assay provides low limits of quantification for simultaneous determination of MDEA, MDMA, and metabolites MDA, HMMA, and HMA in human plasma. The 2D chromatographic system should be suitable for application to other analytes and to other complex matrices.