Screening determination of four amphetamine-type drugs in street-grade illegal tablets and urine samples by portable capillary electrophoresis with contactless conductivity detection

•Simple and inexpensive method for determination of ATS drugs with portable CE-C4D.•Quick screening of ATS prior to further confirmation by costly GC-MS was possible.•ATS drugs were found in illegally used tablets and urine samples in Vietnam.

A simple and inexpensive method for the identification of four substituted amphetamines, namely, 3,4-methylenedioxy methamphetamine (MDMA), methamphetamine (MA), 3,4-methylenedioxy amphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) was developed using an in-house constructed semi-automated portable capillary electrophoresis instrument (CE) with capacitively coupled contactless conductivity detection (C4D). Arginine 10 mM adjusted to pH 4.5 with acetic acid was found to be the optimal background electrolyte for the CE-C4D determination of these compounds. The best detection limits achieved with and without a sample preconcentration process were 10 ppb and 500 ppb, respectively. Substituted amphetamines were found in different seized illicit club drug tablets and urine samples collected from different suspected users. Good agreement between results from CE-C4D and those with the confirmation method (GC-MS) was achieved, with correlation coefficients for the two pairs of data of more than 0.99.