Identification and quantification of 4-methylethcathinone (4-MEC) and 3,4-methylenedioxypyrovalerone (MDPV) in hair by LC-MS/MS after chronic administration

- First method allowing simultaneously measurement of 4-MEC and MDPV in hair.
- Very sensitive method with LLOQ set at 1 pg/mg for both compounds.
- First 4-MEC result in hair in a chronic abuser of this compound.

4-Methylethcathinone (4-MEC) and 3,4-methylenedioxypyrovalerone (MDPV) are synthetic cathinones. The objective of this study was to develop a method in order to measure these compounds in hair of a patient. After decontamination, 20 mg of hair were grinded and incubated in phosphate buffer pH 5.0 in presence of 100 ng of MDMA-d5 used as internal standard. Double basic liquid-liquid extraction was performed. Samples were separated on a 1.9 μm Hypersil GOLD PFP column (100 × 2.1 mm) using gradient elution. Compounds were detected by a LCQ TSQ Vantage XP triple-quadrupole mass spectrometer. SRM transitions m/z 192.1 → 146.1 and 174.2, m/z 276.1 → 175.0 and 205.1 and m/z 199.1 → 165.1 were used for 4-MEC, MDPV and IS, respectively. The assay was accurate and precise over the range 0.001 (lower limit of quantification) to 1 ng/mg in hair. No matrix effect was observed. The method has been applied to a 30-year-old man who usually consumed cathinones for 6 months administered intravenously and was admitted to a general hospital for delirious and tachycardia after absorption of 10 g of a powder sold as 4-MEC and 5 g of MDPV. Both 4-MEC (30 ng/mg) and MDPV (1 ng/mg) were identified in the hair at high concentrations showing a regular consumption of these drugs. Many others compounds were also identified (mephedrone, MDMA, MDA, cocaine and metabolites, tramadol, hydroxyzine, aripiprazole, haloperidol). Few data are available on concentration of these new designer drugs in hair however important in order to determine the acute or chronic consumption of these drugs.