Disposable screen-printed carbon-based electrodes in amperometric detection for simultaneous determination of parabens in complex-matrix personal care products by HPLC

Parabens are chemicals widely used as preservatives in different types of industrial products. In recent years, the concern about the safety of these compounds has increased due to their endocrine disrupting activity. For this reason, their use is highly regulated and even some of them have already been banned. Thus, methods for the sensitive and selective detection of these compounds are required to control their presence in food, cosmetic, and pharmaceutical products. This paper presents an HPLC method with electrochemical detection using disposable screen-printed electrodes (SPE) for simultaneous determination of 6 different parabens in personal care products. Electrochemical behaviour of parabens was studied on SPE with different carbon-based materials as working electrode: carbon, ordered mesoporous carbon and graphene. From these studies, pH, detection potential, and the most adequate SPE were chosen. Due to the wide range of textures and viscosities (e.g., liquid, solid, and semi-solid) of personal care products, adequate sample pretreatments are required before chromatographic measurement. Here, a fast ultrasound-assisted extraction method was applied to simultaneously extract 6 parabens (methyl-, ethyl-, isopropyl-, propyl-, butyl-and benzyl-paraben) from different complex-matrix cosmetic products. Instrumental limits of detection between 20 and 115 μg L⁻¹ were obtained applying +1.0 V (vs. Ag) as detection potential on carbon-based SPE. The total analysis time, including sample extraction and HPLC run, was shorter than 35 min. The proposed method is more versatile and faster than the current available methods and has been successfully applied to determine parabens in commercial samples such as shampoos, body creams, facial tonics, and toothpastes.