Origami chips: Development and validation of a paper-based Lab-on-a-Chip device for the rapid and cost-effective detection of 4-methylmethcathinone (mephedrone) and its metabolite, 4-methylephedrine in urine

4-methylmethcathinone (mephedrone) has emerged in drug seizures as a new psychoactive substance (NPS) causing a public health risk of global concern. Currently, there are no commercial microfluidic devices for the selective detection of mephedrone and so this study presents a simple, low-cost and portable paper-based Lab-on a-Chip (LOC) device with colorimetric detection to fill this gap. Limits of detection for mephedrone in spiked urine and dissolved powder (aqueous) samples are clinically relevant at 4.34 ng mL(-1) and 2.51 ng mL(-1) respectively. No cross-reactivity for commonly encountered cutting agents, interferents and adulterants were detected. Mephedrone and its main metabolite were detectable in aqueous and urine samples within 3 min. Stability and reproducibility measurements showed no significant difference in signal intensity over eight weeks and no significant difference within or between devices. The proposed device has the potential to provide costeffective, rapid, on-site testing within forensic or clinical settings and therefore has wide global applicability.

Automated summary

The study introduces a simple, low-cost, and portable paper-based Lab-on-a-Chip device with colorimetric detection for selective detection of mephedrone. It has clinically relevant limits of detection and shows potential for cost-effective, rapid, on-site testing within forensic or clinical settings, with global applicability.