Enantioselective analysis of amphetamine-related designer drugs in body fluids using liquid chromatography and solid-phase derivatization

A method for the enantioselective determination of the amphetamine-derived designer drugs 3,4-methylenedioxymethamphetamine (MDMA), 3,,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxyethylamphetamine (MDE) based on their derivatization with (-)-1-(9-fluorenyl)ethyl chloroformate (FLEC) is described. The proposed procedure entails preconcentration and derivatization of the analytes into C-18-packed solid-phase extraction cartridges, chromatographic separation of the diastereomers originated in a C-18 column under gradient elution, and UV detection at 265 nm. Compared with the solution derivatization approach the described procedure increased analyte responses by factors of 28-58. The reliability of the method has been tested by analysing plasma and urine samples spiked with the analytes in the 0.015-1.0 mug mL(-1) concentration interval. The proposed conditions provided adequate linearity, and coefficients of variation ranging from 5% to 14% in plasma, and from 3% to 2% in urine. The recoveries of the analytes were of 78% - 126% and 78% - 128% in plasma and urine, respectively. The limits of detection (LODs) obtained for all the analytes were 5 ng mL(-1) in both biological matrices.