## 1 Introduction  
Nowadays, there is a proliferation, at an unprecedented scale, of new illicit drug discoveries on a global scale. To get around existing drug laws, manufacturers are developing new analogs by the modification of the chemical structure of known compounds. As a result, new psychoactive substances (NPS) are on the increase, and the illicit drug market has continued to expand over the last decade [1, 2, 3]. Up until the end of 2021, a total of 1127 different NPS were ever reported by 134 countries worldwide to the United Nations Office on Drugs and Crime (UNODC), but only 302 of them are under international control so far [4]. The global popularity of NPS is rather ominous, and the associated serious public health hazard has been gaining more attention. With the development of chemical techniques, most NPS have a short currency as some of them might been replaced by other analogues with better effects in the market [4]. Analytical laboratories of public security departments are thus confronted by the challenge of having to detect the appearance of such NPS in time. As one of the most popular NPS, synthetic cathinones are widely abused and often sold as \"ecstasy\" as they have central-nervous-system-stimulant and hallucinogenic effects [4, 5]. Manufacturers of novel drugs keep looking for alternatives, and a cumulative number of 201 synthetic cathinones were reported to UNODC by 2021 [4]. UNODC has summarized and recommended different methods to identify and analyze synthetic cathinones in seized materials [6]. The conventional methods for synthetic cathinone detection are mainly mass spectrometry (MS) [7; 8; 9; 10], nuclear magnetic resonance (NMR) spectroscopy [11; 10; 12], Fourier-transform infrared (FTIR) spectroscopy [12], and Raman spectroscopy [13]. However, most of the instruments mentioned above are too bulky to allow portability, and are not only expensive but also need time-consuming operation. Although several methods using handheld instruments have been developed for on-field drug analysis [14; 15; 16], research results in this area are limited and synthetic cathinone detection still requires sensitive and portable devices for rapid screening on-site. With the advantages of high sensitivity, portability, the low cost of instrumentation, and simplicity for operators, the electrochemical approach is an in-field detection method that has prevailed in recent years [17]. To this end, the use of screen-printed electrodes were shown to detect synthetic cathinones and metabolites [18; 19; 20; 21]. Previous reports [22] have shown that the affinity and selectivity of electrochemical sensors could be improved by molecularly imprinted polymers (MIPs) with the advantage of having synthetic polymeric recognition elements. Notably, it has been previously reported that MIPs can be developed as extraction and quantification material for NPS [23]. MIPs are polymeric synthetic receptors which can be tailored towards different templates, and this makes them a very powerful tool for the selective extract traces of targets from complex samples [24; 25]. Therefore, the combination of electrochemical sensors and MIPs is an effective way to overcome the drawbacks of traditional methods for NPS detection, offering an excellent opportunity to develop rapid analytical approaches with high selectivity. Traditionally, MIPs were prepared by bulk polymerization, but the deep embedment of the recognition sites within the thick polymer network would inevitably result in high diffusion barriers, low-affinity binding, and low-rate mass transfer [26]. An efficient approach to overcome these limitations is to construct such molecular recognition sites on support materials, which is known as the surface-imprinting method [27]. Significantly, MIP film coated carbon nanomaterials have been developed in recent years as transducer platforms with good electrical conductivity [28].