Enantioselective determination of cathinone derivatives in human hair by capillary electrophoresis combined in‐line with solid‐phase extraction

Abstract

A suitable method has been developed and validated for the chiral separation and determination of R,S-mephedrone and one of its metabolites, R,S-4-methylephedrine, and R,S-methylenedioxypyrovalerone (R,S-MDPV) in human hair samples by the in-line coupling between SPE and CD-assisted CE with a previous sample pretreatment procedure based on pressurized liquid extraction. Optimum separation was achieved on a fused silica-capillary of 50 μm id and 80 cm total length using 12 mg/mL β-CD in an aqueous solution of 80 mM disodium phosphate at pH 2.5 as the BGE and an applied voltage of 30 kV. The SPE-CE device consists of a short length of a capillary of 2 mm packed with Oasis HLB sorbent, which was inserted near to the inlet end of the CE capillary. Several parameters affecting the in-line preconcentration were evaluated. The LOQs reached for hair samples were 0.05 ng/mg for the enantiomers of mephedrone and its metabolite, and 0.40 ng/mg for the enantiomers of MDPV. The RSDs (%) obtained in intra- and interday studies were less than 10% and the relative recoveries were greater than 80%. The method established in this paper is advantageous for its simplicity, overall analysis time and ability to provide information of both enantiomers of a chiral drug in hair samples.

Chiral and stable isotope analysis of synthetic cathinones

“…Enantiomers of all three were not well separated by native β-CD but the resolutions were improved using S-β-CD (R s = 1.3, 1.7 and 6.4 respectively). In contrast, a recent study showed that S-β-CD did not work as expected but native β-CD enabled the chiral separation of 4-methylmethcathinone (4-MMC) and 3,4-methylenedioxypyrovalerone (3,4-MDPV) [29], possibly because of the different experimental conditions applied such as the identity and pH value of buffer solution.…”

Chiral determination of 3,4-methylenedioxypyrovalerone enantiomers in rat serum

“…While our method also does not attain the level of chiral resolution seen in the similar Silva et al 14 described method, it did achieve a 400-fold improvement in the LLOQ compared to the quantitative Baciu method. 15 …”

“…Baciu et al report a chiral quantitative capillary electrophoresis method for the determination of MDPV enantiomers in hair, with a lower limit of quantitation (LLOQ) of 0.4 ng/mg which equates to about 400 ng/ml. 15 Considered together, none of these chiral selective methods were designed for quantitation of the low ng/ml concentrations of MDPV enantiomers expected in rodent pharmacokinetic studies with small serum or plasma sample volumes (20 – 50 µl).…”

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2016–2018)

“…Satisfactory recoveries ranging from 81 to 95% were obtained for all analytes. The same group constructed a similar SPE column for the preconcentration of racemic mephedrone and its metabolites, whereby LOD as low as 0.02 ng/mg was achieved for one of the enantiomer . The similarity from both works was that the authors managed to minimize current instability and breakdown during the CE separation, a common issue when conducting in‐line SPE using discontinuous packed bed in the same capillary with CE separation.…”

“…Schematic illustration of the different steps of cis‐diols compounds analysis: preconcentration and purification on the integrated μBAMC unit, acidic elution, CZE separation and UV detection. Reprinted from with permission.…”