Developing a carbamate insecticide isoprocarb mini sensor based on electrochemiluminescence of luminol on screen-printed carbon electrodes

A carbamate insecticide isoprocarb mini sensor has been successfully developed based on the electrochemiluminescence (ECL) of luminol on a screen-printed carbon electrode (SPCE). Weak ECL signals were observed upon excitation potential luminol at +0.3 V (vs. Ag/AgCl). These signals are amplified multiple times by the addition of hydrogen peroxide (H₂O₂). On the other hand, the presence of isoprocarb reduces these ECL signals, which was used as an analytical tool for isoprocarb sensing. To achieve highly precise and accurate results, the optimization was conducted by varying the contact time, pH, scan rate, and concentration of H₂O₂ as a coreactant. The assay duration of 20 min (min) was determined to be the optimal reaction time between isoprocarb and luminol, offering an effective balance between sensitivity and stability of the ECL signal. The ECL signals of luminol show a linear correlation (R² = 0.99) against the concentrations of isoprocarb in the range of 6 to 150 nM. The developed sensor provides low limits of detection and quantification of 5.1 and 15.6 nM, respectively, exhibits better sensitivity compared to other electrochemical and nonelectrochemical sensors. The developed sensor also showed a high selectivity toward isoprocarb in the presence of some interferences with RSD values below 5%. Moreover, a remarkable stability across 5 measurements on different days was examined with an RSD value of 2.0%. The results indicate that the developed sensor has a significant potential for the isoprocarb detection.