Simultaneous derivatization and extraction of amphetamine-like drugs in urine with headspace solid-phase microextraction followed by gas chromatography–mass spectrometry

Abstract

A sensitive and solvent-free procedure for the determination of amphetamine-like drugs, amphetamine (AM), methamphetamine (MeAM), methylen-dioxyamphetamine (MDA), methylen-dioxymethamphetamine (MDMA) and methylen-dioxyethylamphetamine (MDEA) in urine samples was developed using solid-phase microextraction (SPME) with an on-fiber derivatization device. In this study, the amphetamine-like drugs were derivatized with heptafluorobutyric anhydride (HFBA) and heptafluorobutyric chloride (HFBCl) and determined by means of a gas chromatography–mass spectrometer with selected ion storage (SIS) detection. An improved design was used for sample preparation. The test specimen was placed in an 8 ml vial along with additives (KOH and NaCl), a glass insert with twelve holes containing the derivatizing reagents was inserted into the vial, and the vial was then sealed tightly. A SPME device with a 100 μm polydimethylsiloxane fiber was inserted into the vial and the fiber was exposed to the headspace in the insert, then the vial was heated and stirred at 95 °C and 600 rpm for 30 min for evaporation/adsorption/derivatization. The SPME needle was finally removed and inserted into the GC injection port to desorb the analytes. The influence of several parameters on the efficiency of microextraction (type of fiber coating, extraction time, extraction temperature, etc.) was investigated. The SPME method developed provides good sensitivity with a calibration range from 0.5 to 1000 ng ml −1 for MDA, and 0.1–1000 ng ml −1 for AM, MA, MDMA and MDEA. The method detection limits (MDLs) are in the range 0.016–0.193 ng ml −1 with the studied drugs. This method was also successfully tested on real samples of urine from people who were suspected of using amphetamines.