The application of portable microchip electrophoresis for the screening and comparative analysis of synthetic cathinone seizures

• MEC method developed for the rapid screening of synthetic cathinones.
• Method assessed on real seizures in New Zealand.
• Use of MEC profiles in realistic scenarios discussed.
• Analysis of a large number of tablets without increasing the burden on laboratories.

Variation in the chemical composition of illicit tablets and powders is common among samples within a given drug seizure. Using microchip electrophoresis (ME), multiple tablets can be screened in a cost-effective and timely manner. This method could be used in conjunction with reporting methods that focus solely on statistical sampling to infer homogeneity or otherwise of a larger subset of tablets. Some frequently observed synthetic cathinones, often present in illicit tablets seized in New Zealand, were chosen for analysis. An ME device (Agilent Bioanalyzer 2100) was used to electrophoretically separate synthetic cathinones. The background electrolyte was composed of a 50 mM sodium tetraborate buffer with 50 mM sodium dodecyl sulphate at pH 9.66. Analytes were derivatised prior to analysis for 3 min at 90 °C, employing fluorescein isothiocyanate isomer I (FITC). A characteristic fluorescent profile was obtained for each tablet, in terms of the number of constituents, relative peak height ratios and migration times. The repeatability of the developed method was assessed for a wide range of tablets and relative standard deviations of 0.4–5.2% and 1.6–5.5% were calculated for migration times and peak height ratios, respectively. The use of microchip tablet profiles in the forensic case comparison of illicit drug seizure samples in realistic scenarios is discussed.