Mixed-Mode Solid-Phase Extraction Procedures for the Determination of MDMA and Metabolites in Urine Using LC-MS, LC-UV, or GC-NPD

A solid-phase extraction method using a mixed-mode cation exchange cartridge effectively cleans and concentrates MDMA and its metabolites MDA and HMMA from urine for analysis by liquid chromatography–mass spectrometry. Recoveries ranged from 88% to 108% across concentrations of 0.10 to 20 micrograms per milliliter. The LC-MS method required the least sample handling, offered the highest throughput, and provided better selectivity for HMMA in real samples compared with LC-UV. GC with nitrogen-phosphorus detection gave comparable selectivity but involved more manipulation, leading to lower recovery and precision. Lower quantitation limits were 0.1 microgram per milliliter for MDMA and MDA and 0.04 microgram per milliliter for HMMA.

Study at a glance

Abstract

A solid-phase extraction (SPE) procedure was developed for the liquid chromatographic-mass spectrometric (LC-MS) analysis of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolites 3,4-methylenedioxyamphetamine (MDA) and N,alpha-dimethyl-(3-methoxy-4-hydroxybenzene) (HMMA) ethanamine in urine. The procedure, with modifications, was also demonstrated using LC-UV and GC-nitrogen-phosphorus detection (NPD). A mixed-mode cation exchange SPE cartridge was effective for both reducing matrix impurities and for preconcentrating the analytes for the analysis. The concentration range investigated spanned from 0.10 to 20 microg/mL with recoveries ranging from 88% to 108% for all analytes using LC-MS. Both LC methods and the GC method allow for complete resolution of MDMA, MDA, and HMMA, as well as the internal standards (MDMA-d5 and 3,4-methylenedioxypropylamphetamine) in less than 10 min. Lower limits of quantitation (LLOQ) for the LC-MS method were 0.1 microg/mL for MDMA and MDA and 0.04 microg/mL for HMMA. Compared with LC-UV and GC-NPD, the LC-MS method requires the least amount of sample manipulation and provided the highest sample throughput. GC-NPD gave comparable selectivity, but the extra sample manipulation steps required contributed to lower recovery, lower precision, and increased time for the analysis. LC-MS analysis demonstrated better selectivity for the determination of HMMA in incurred samples compared with LC-UV analysis.