Simultaneous square wave voltammetric determination of 2-mercaptobenzothiazole and 2-mercaptobenzoxazole by partial least squares method in water samples

A rapid sensitive and versatile method for simultaneous determination of 2-mercaptobenzothiazole (MBT) and 2-mercaptobezoxazole (MBO) based on the square wave voltammetric (SWV) using mercury drop electrode (SMDE) has been presented. A three-electrode system containing SMDE working electrode, Pt auxiliary electrode and Ag/AgCl reference electrode was used throughout. The linear calibration graphs are in the concentration range of 7-40 μg mL−1 and the equations are: (Δi) = 1.372CMBT − 9.112 (r = 0.9982) and (Δi) = 0.246CMBO − 1.736 (r = 0.9985) for MBT and MBO, respectively. Partial least squares regression (PLS) was applied to resolve the seriously overlapped voltammograms without any pre-separation step. The five level partial factorial design was used as calibration design method and the cross-validation method was used to select the number of significant factor for PLS model building. Five significant PLS components are used for MBT and MBO. A set of synthetic sample mixtures were used to validate the propose method. The root-mean-square errors of predictions (RMSEPs) and percent of relative prediction errors (RPEs) are 0.841 and 0.777 μg mL−1 and ±3.58 and ±3.74% for MBT and MBO, respectively. The developed method was then applied to the analysis of these two compounds in different water samples with satisfactory results.