Electrode modified with graphene quantum dots supported in chitosan for electrochemical methods and non-linear deconvolution of spectra for spectrometric methods: approaches for simultaneous determination of triclosan and methylparaben.

Two analytical methods were developed using electrochemical and spectrometric techniques for the simultaneous determination of endocrine disruptors triclosan and methylparaben in the monitoring of personal care products. For the electroanalytical analyses, a sensitive electrode based on graphene quantum dots supported in chitosan was employed. Under optimized conditions and a working potential of typically + 0.60 V for triclosan and + 0.81 V (vs. Ag/AgCl) for methylparaben, the calibration plots obtained by differential pulse voltammetry were linear in the range 0.10 to 10.0 μmol L-1. The detection limits were 0.03 and 0.04 μmol L-1 for triclosan and methylparaben, respectively. For the spectrometric method, UV/VIS spectrometry was used with a mathematical processing of non-linear deconvolution. This processing was used to solve the problem of overlapping absorption bands of triclosan (282 nm) and methylparaben (257 nm), which enabled simultaneous determination. The calibration plots by UV/VIS spectrometry were linear in the range 1.0 to 14.0 μmol L-1 with detection limits of 0.42 and 0.37 μmol L-1, respectively, for triclosan and methylparaben. Similar results obtained from the calibration plots of individual analytes suggest that the methods can be applied for individual or simultaneous determination of these species. Both methods were employed in the analysis of five samples of personal care products: toothpaste, antiseptic soap, antiseptic deodorant, shampoo, and a bath kit (soap and shampoo). The statistical tests indicated that there were no significant differences regarding the accuracy and precision of the data provided by the two methods described herein. Graphical abstract Schematic representation for simultaneous determination of triclosan and methylparaben: electrochemical method employing an electrode modified with graphene quantum dots supported in chitosan and spectrometric method applying a non-linear deconvolution of spectrum.