Trace detection of methcathinone in sewage using targeted extraction based on magnetic molecularly imprinted polymers coupled with liquid chromatography-tandem mass spectrometry

Methcathinone, a new psychoactive substance (NPS), poses a serious threat to public health. Therefore, there is an urgent need to develop a reliable, selective, sensitive and simple analytical technique for monitoring trace amounts of this target NPS in complex matrices. For this purpose, magnetic molecularly imprinted polymers (MMIPs) based on MIPs combined with nano-sized magnetic Fe₃O₄ were developed for the specific enrichment of methcathinone in wastewater. The binding properties and selectivity of MMIPs toward methcathinone were evaluated and compared with non-imprinted polymer (MNIPs). For sensitive and selective extraction and determination of the target methcathinone, magnetic solid-phase extraction (MSPE) based on MMIPs was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under optimized conditions, the proposed method was successfully used for the detection of methcathinone in wastewater, which provided a low limit of detection of 0.3 ng L^-1 and a limit of quantification of 1.0 ng L^-1 with relative standard deviations of less than 6.89% for intra- and inter-day analyses. Good linearity in the range of 1-2000 ng L^-1 with a coefficient of determination (R²) greater than 0.98 was observed. Moreover, a certified reference material of water sample was successfully analyzed with satisfactory results and the recoveries of spike experiments ranged from 96.35-116.7%.