Electrochemical Sensing and Assessment of Parabens in Hydro- Alcoholic Solutions and Water Using a Boron-Doped Diamond Electrode

Abstract

In this paper, the electrochemical behaviour of several parabens preservatives, i.e. esters of p-hydroxybenzoic acid, methyl-, ethyl- and propyl-4-hydroxybenzoates as methyl-, ethyl- and propyl-parabens (MB, EB, and PB), has been investigated at a commercial boron-doped diamond electrode (BDDE), especially in the anodic potential range, in both hydro-alcoholic and aqueous media. The cyclic voltammetric and chronoamperometric measurements yielded calibration plots with very good linearity (R2 between 0.990 and 0.998) and high sensitivity, useful for detection and analytical applications. The determination of the characteristics of individual compounds, of an “overall paraben index”, the assessment of the stability and the saturation solubility in water, and the amperometric sensing and determination in double distilled, tap and river water matrix of the relatively slightly soluble investigated parabens have been carried out using electrochemical alternative. Estimated water solubility was correlated with the octanol-water partition coefficient. Several ideas regarding stability and persistence of the presumptive eco-toxic investigated preservatives in the environment or water systems have been adjacently discussed.

Anodic oxidation of parabens in acetic acid–acetonitrile solutions

“…The results obtained show that parabens cannot be electrochemically identified in this medium. The same conclusions were drawn from the earlier electrochemical investigations [8,[29][30][31]] (see Sect. 1).…”

“…3) and the steady-state current is similar to that observed for its esters. The similarity of the voltammetric curves recorded in hydro-alcoholic solutions containing PHB or its esters was reported by Radovan et al [30]. The same potential region for the anodic oxidation of these compounds can be related to comparable charge densities on the oxygen atom in the hydroxyl group for PHB (-0.219) and parabens.…”

“…As the literature data suggest, the electrochemical oxidation of phenolic compounds can induce a passivation of the working electrode via deposition of a polymeric film on their surface which is formed by polymerization reactions of phenoxyl radicals [44][45][46][47]. Similar and negligible adsorption phenomena accompanying the anodic oxidation of parabens were also observed in hydro-alcoholic solutions [30]. In order to ensure the reproductivity of curves recorded by LSV, the surface of the CF microelectrode always needed to be polished between measurements.…”

“…These results were explained in terms of enhancing the diffusion of the analyte to the surface of the working electrode. The same BDD electrode was employed by Radovan et al [30] for the determination of parabens in hydro-alcoholic solutions by cyclic voltammetry (CV) and chronoamperometry. Since all parabens investigated (MP, EP, and PP) are oxidized in aqueous solutions containing 20 % of ethanol (v/v) giving Scheme 1 Molecular structures of PHB and their derivatives (parabens) one anodic peak at the same potential of about 0.9 V (vs. SCE), it is possible to determine only the total amount of parabens, named by the authors as ''overall paraben index''.…”

“…They were mainly examined to evaluate the optimal conditions for their determination in real samples using electrochemical detectors [8,[29][30][31]. Wang et al [29] suggested a rapid and reliable electrochemical method to determine the total content of parabens in cosmetics on a GC electrode modified with polymers (MIPs) containing MP and PP as dual templates.…”