A novel method based on electrochemical approaches and multivariate calibrations for study and determination of methylparaben in the presence of unexpected interference in cosmetics

The use of multivariate voltammetric calibration for the simultaneous determination of two preservatives (methylparaben (MP) and propylparaben (PP)) in cosmetics is reported. At first, electrochemical studies of MP and PP were done by cyclic voltammetry (CV), chronocoulometry (CHC) and linear sweep voltammetry (LSV) techniques. Then central composite rotatable design (CCRD) and response surface methodology (RSM) were used for simultaneous optimization of effective parameters on voltammetric responses of the two analytes. The optimum values of pH, scan rate, step potential and pulse height were 7.0, 0.062 V s−1, 0.009 V and 0.07 V, respectively. After optimization, the resolution of the two multicomponent mixtures has been accomplished by partial least squares (PLS) for voltammmetric studies of them at the surface of a glassy carbon electrode. Finally, the proposed method was found to be applicable for routine analysis (recovery tests) of the preservatives in a cosmetic product.