Detection of Methylparaben in Cosmetics by Poly L–Lysine/Reduced Graphene Oxide-Based Sensor

In this study, a PoL/RGO material was successfully synthesized and employed to modify the working electrode for determining MPB in medication products through voltammetric techniques. The structure of the nanocomposite was characterized by UV–vis and FT-IR spectrum and its application to the MPB electrochemical detection was tested by the CV and DPV techniques. In the result, the modified PoL-RGO/GCE electrode exhibited a superior response toward MPB by applying the DPV method, compares to using the bare GCE, with a limit of detection (LOD), a limit of quantification (LOQ) is 0.20 μM and 0.70 μM, respectively and the concentration ranging from 1 to 200 μM. In addition, the repeatability (RSD of 2.2, 1.6, 1.4 for 5, 50 and 100 μM MPB, respectively), and the reproducibility (RSD of 4.7%) of the technique were examined as well. This illustrates the performance of the electrochemical sensor was statistically investigated by the CV and DPV methods demonstrating accuracy comparable to other analytical methods as well as indicating that MPB can be determined in cosmetics with high recovery ranging from 97% to 104.3%.