Adsorptive stripping square wave voltammetry (Ad-SSWV) accomplished with second-order multivariate calibration: Determination of fenitrothion and its metabolites in river water samples

Abstract

A method, using stripping square wave voltammetry (Ad-SSWV), for the simultaneous determination of fenitrothion (FEN) and its metabolites: fenitrooxon (OXON) and 3-methyl-4-nitrophenol (3-MET) in environmental samples is reported. All three compounds produce, at mercury electrode (HMDE), an electrochemical signal due to an adsorptive–reductive process. The electrochemical approach shows a very high overlap degree for FEN and OXON voltammograms, however the adsorption kinetic profile could be used as an additional differential variable between both analytes. Second-order multivariate calibration has been tested to solve the mixture of the three compounds. The second-order assayed methods were parallel factor analysis (PARAFAC), unfolded partial least squares (U-PLS), multidimensional partial least squares (N-PLS) and the latest ones were used in combination with the residual bilinearization procedure RBL. U-PLS/RBL model was stated as the best second-order algorithm for the simultaneous determination of these three compounds up to 50 ng mL −1 for each analyte. The detection limits and recovery values were 1.6 ng mL −1 and 92 ± 7% for FEN; 3.7 ng mL −1 and 101 ± 9% for OXON and 0.6 ng mL −1 and 97 ± 8% for 3-MET.