ABSTRACT
A gas chromatography-mass spectrometry (GCMS) procedure was developed for the quantitative analysis of the new designer drug methylenedioxypyrovalerone (MDPV) in urine together with the common stimulants amphetamine, methamphetamine, and methylenedioxymethamphetamine (MDMA). The procedure involved electron ionization (EI) GCMS in the selected ion monitoring (SIM) mode after liquid-liquid extraction with toluene and derivatization with heptafluorobutyric acid anhydride. All MDPV findings were confirmed by positive chemical ionization GCMS in SIM mode. Positive chemical ionization-GCMS allowed the protonated molecule M+H+ m/z 276 to be used as a target ion with 3 abundant fragments as qualifier ions. By electron ionization-GCMS, the limit of quantification (LOQ) for MDPV was 0.02 mg/L; and for amphetamine, methamphetamine, and MDMA, the LOQ was 0.05 mg/L. The method was applied to monitoring urine samples from opioid-dependent patients undergoing opioid substitution treatment. Nine of the 34 urine samples (26%) analyzed were MDPV positive by the GCMS procedure. The positive samples were obtained from 2 female and 7 male patients with a mean age of 31 years. The median (range) MDPV concentration was 0.16 mg/L (0.04-3.9 mg/L) based on the 7 samples for which a numeric value was obtained, whereas the concentration was below the LOQ but above the limit of detection in 2 samples. The method revealed amphetamine in approximately 40% of the cases, and there was no statistical difference between the MDPV-positive and MDPV-negative groups. Urine amphetamine concentrations were on average 10 times higher than those of MDPV. The opioid-dependent patients used MDPV mainly as a substitute for amphetamine, judging from the laboratory findings of this study and the information from our patients.
