Simultaneous Spectrophotometric Quantification of Crystal Violet and Malachite Green in Aqueous Samples: Combination of Multivariate Calibration Method and Solid Phase Extraction Based on Sodium Dodecyl Sulfate (SDS) Grafted Chitosan Nano-composite

A simple solid phase extraction (SPE) based on sodium dodecyl sulfate grafted chitosan nanocomposite was applied for simultaneous spectrophotometric determination of crystal violet (CV) and malachite green (MG) content of water samples. For the data analysis of the overlapped spectra of the two dyes, the partial least square regression (PLSR) has been utilized. The synthesized sorbent was characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results showed the SDS was successfully cross-linked with the chitosan. Various parameters affecting the simultaneous extraction of the analytes, such as pH of sample solution, sample flow rate and the volume and flow rate of eluent were optimized by central composite design and response surface methodology (RSM). Figures of merits consisting of sensitivity, analytical sensitivity, limits of detection (LOD) and limit of quantitation (LOQ) were calculated to 0.89 ng ml-1, 762.07, 0.06 ng ml-1 and 0.20 ng ml-1 for CV, and 0.15 ng ml-1, 128.24, 0.17 ng ml-1 and 0.53 ng ml-1 for MG. The calibration curve showed high correlation coefficients of 0.9995 and 0.9993 for CV and MG, respectively. Moreovere, preconcentration factor and extraction recovery of the analytes were computed based on the regression coeffients of PLSR acting as a multivariate net analyte signal filter.