In this study a Glassy carbon electrode (GCE) modified with nickel oxide nanoparticles was developed. This electrode has a good sensitivity and electrocatalytic activity toward the oxidation of propanil and monalide over a wide concentration range. The propanil and monalide oxidation mechanism on the electrode surface was investigated, and the overall number of electrons involved in the electrocatalytic oxidation was found to be 3. The detection limit of this electrode for determination of propanil and monalide was 0.05 and 0.21 μM and its relative standard deviation for 10 independent measurements was 3 and 3.7%, respectively. Finally the proposed electrode exhibited several advantageous features, including simple preparation, fast response time, and good repeatability. The electrode was successfully applied for simultaneous determination of propanil and monalide based on partial least squares (PLS) regression with orthogonal signal correction (OSC) and wavelet packet transform (WPT) as pre-processing tools with overlapping peaks. In this case, by optimization, the kind of wavelet function, the decomposition level, the number of OSC components and number of PLS factors for the OSC-WPT-PLS method were selected as Daubechies 3, 1, 1 and 4, respectively. The relative standard errors (R.S.E) of prediction obtained for two components using OSC-WPT-PLS, WPT-PLS and PLS were compared. Experimental results demonstrated that the OSC-WPT-PLS method produced the best results among the three methods.
