The MIP-coated carbon paper electrode was applied for selective MTZ determination using DPV in the presence of Ru(NH3)6Cl3 redox probe (Figure ). For that purpose, we have exploited so called "gate effect" . In theory it is assumed that binding of analyte into MIP's imprinted cavities affect diffusion of redox probe through the film to electrode surface, resulting in changes of recorded current. Alternatively, in past we have proven that in case of conductive MIP films changes of MIP film conductivity due to analyte binding can be predominant factor influencing signal originating from redox probe . Here in, the Ru(NH3)6Cl3, diffusion of a positively charged redox probe, toward negatively charged MIP modified electrode was enhanced. In this condition, subsequent changes in current (increase) during DPV measurements allowed for the quantitative determination of the analyte. In this case, DPV peak current increased with MTZ concentration increase from 0.2 to 200 nM (Figure ). The response of the MIP film-coated carbon electrode was very well described by Langmuir-Freundlich isotherm (Figure , and Table ). The described system is characterized by a low value of homogeneity factor, namely, n = 0.135, indicating scarcely homogeneous distribution of molecular cavities in the polymer matrix . We may speculate that this is because of the highly developed surface of the carbon paper electrode, nevertheless the performance of our fabricated chemosensor is satisfactory. However, from a practical point of view, it is more convenient to use linear fitting. The linear fitting enables easier comparison of the analytical parameters of the sensor. For that purpose, a linear calibration curve with respect to the logarithm of MTZ concentration was filed (Figure ). The calibration plots followed the linear equation ( The main purpose of decorating electrodes with MIP films is to introduce selective recognition. Therefore, MIP film-coated electrode response toward chosen interfering compounds, including glyphosate, creatinine, L-ascorbic acid, glucose, penicillin G, and vancomycin was tested (Figure ). Only in the case of glucose, it was possible to calculate selectivity factor and it was equal to 17.9. In case of other interfering compounds sensors response were completely negligible, or changes were in the opposite direction compared to MTZ. However, absolute values of these changes were much lower than sensors response to MTZ and it may be concluded that MIP sensor selectivity was high.