Microwave-induced rapid preparation of fluoro-derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine for GC-MS confirmation assays

We prepared trifluoroacetyl, pentafluoropropyl, and heptafluorobutyl derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in 45 s, 1 min, and 6 min, respectively, by using microwave irradiation. Conventional techniques require heating the reaction mixture for 15 min at 40 degrees C for trifluoroacetyl derivatives, 15 min at 75 degrees C for pentafluoropropyl derivatives, and 40 min at 60 degrees C for heptafluorobutyl derivatives. The mass-spectral fragmentation patterns and the gas-chromatographic retention times of the derivatives obtained by both microwave irradiation and conventional heating were similar. Perfluorooctanoyl derivatives of amphetamine can be prepared quantitatively by either heating the reaction mixture for 30 min at 60 degrees C or by 1 min of microwave irradiation. Conversion of methamphetamine and MDMA to the corresponding perfluorooctanoyl derivatives was not quantitative by either technique, although the yield of the derivative in the conventional technique was much higher.