A novel amperometric sensor based on screen-printed electrode modified with multi-walled carbon nanotubes and molecularly imprinted membrane for rapid determination of ractopamine in pig urine

Screen-printed electrodes were modified with multi-wall carbon nanotubes (MWCNT) and molecularly imprinted membranes (MIM) were directly synthesized on these modified electrodes using the in situ thermal polymerization techniques. The sensing system was easily established by connecting the screen-printed electrode modified with MWCNT-MIM to an electrochemical analyzer through an electrode slot. The signal for the determination of ractopamine was recorded using differential pulse voltammetry (DPV) and the optimization for the experimental conditions was also conducted. The results showed that the response of the sensor to concentration of ractopamine displayed a linear correlation over a range from 20 nM to 200 nM with a detection limit of 6 nM, demonstrating favorable sensitivity and selectivity for the detection of ractopamine. The recoveries reached 87.7–96.9% based on pig urine samples.