Determination of phenmetrazine in urine by gas chromatography-mass spectrometry after liquid-liquid extraction and derivatization with perfluorooctanoyl chloride.

Phenmetrazine is a central nervous system stimulant and is currently used as an anorectic agent. The drug is abused and reported to cause death from overdose. We describe a liquid-liquid extraction protocol for phenmetrazine from urine using 1-chlorobutane and subsequent derivatization using perfluorooctanoyl chloride for gas chromatography-mass spectrometric confirmation. Quantitation of urinary phenmetrazine can be easily achieved by using N-propylamphetamine as an internal standard. The perfluorooctanoyl derivative of phenmetrazine showed a weak molecular ion at m/z 573 and a characteristic strong peak at m/z 467 in the electron ionization mass spectrometry thus aiding unambiguous identification. The perfluorooctanoyl derivative of the internal standard did not show any molecular ion, but showed strong characteristic peaks at m/z 482 and 440. The within run and between run precisions of the assay were 1.7% and 3.2% at a urinary phenmetrazine concentration of 20 microgram/mL. The within run and between run precisions were higher (9.4% and 10.8%) at a urinary phenmetrazine concentration of 1.0 microgram/mL, which was very close to the detection limit of the assay. The assay was linear for urinary phenmetrazine concentration of 1 to 100 micrograms/mL with a detection limit of 0.5 microgram/mL.