Simultaneous spectrophotometric determination of crystal violet and malachite green in water samples using partial least squares regression and central composite design after preconcentration by dispersive solid-phase extraction.

In this paper, a simple, fast, and inexpensive method is introduced for the simultaneous spectrophotometric determination of crystal violet (CV) and malachite green (MG) contents in aquatic samples using partial least squares regression (PLS) as a multivariate calibration technique after preconcentration by graphene oxide (GO). The method was based on the sorption and desorption of analytes onto GO and direct determination by ultraviolet-visible spectrophotometric techniques. GO was synthesized according to Hummers method.

Application of multivariate optimization procedures for preconcentration and determination of Au(III) and Pt(IV) in aqueous samples with graphene oxide by X-ray fluorescence spectrometry.

A simple method was developed for the determination of Au(III) and Pt(IV) contents in aqueous samples after preconcentration. The method was based on the sorption of analytes as 2-amino-5-mercapto-1,3,4-thiadiazol complexes onto graphene oxide and subsequent direct determination by wavelength dispersive X-ray fluorescence (WDXRF). The optimization step was carried out using two-level full-factorial and Box-Behnken designs.