An Electrochemical Sensor for Trimethoprim Based on a Magnetic Molecularly Imprinted Carbon Paste Electrode

In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe3O4@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped with Fe3O4@MWNTs. The introduction of multi-walled carbon nanotubes (MWNTs) and rGO served as dual signal-amplification materials, which can improve the response sensitivity of the sensor. In addition, the magnetic interaction between the substrate electrode and the molecularly imprinted material was beneficial to increasing the stability of the sensor. As expected, the electrochemical sensor not only showed sensitivity and selectivity for the detection of TMP, but it also possessed good stability. The detection range for TMP was 4.0 x 10(-9)similar to 5.0 x 10(-4) mol/L, and the detection limit was 1.2 x 10(-9) mol/L. The response performance varied within 10% when the sensor was placed for more than 2 months and used more than 60 times. The spiked recoveries of TMP in environmental water samples, urine samples, and pharmaceuticals (drugs) were between 91% and 110%, and the relative standard deviation (RSD) was within 5%.