The importance of a reduction step in anodization of glassy carbon electrode for voltametric determination of ibuprofen

Abstract

Electrochemical methods are promising for determination of ibuprofen (IB) – one of the most frequently used analgetic – without complicated sample pretreatment and with cheaper device, comparing to conventional methods (e.g., chromatography). To achieve this, glassy carbon electrodes (GCE) are a good choice with an anodization being a cheap and simple method to enhance voltametric signal towards various types of analytes. In this work, GCEs were anodized by cyclic voltammetry at two potential ranges; an anodizing only (0.8 ➔ 1.6 V; Aa-GCE) and an extended one containing also a reduction part (−1.0 ➔ 1.6 V; Ac-GCE). It was revealed that the reduction is needed to achieve electrocatalytically active surface with Ac-GCE electrodes exhibiting more than six-fold higher voltammetric response towards IB compared to Aa-GCE. Consequently, Ac-GCE was used as the IB sensor with calculated limit of detection and sensitivity 1.5 mg·L−1 and 0.07 μA·L·mg−1, respectively. The sensor's performance was also evaluated through the detection of IB in the commercially available formulations. During repeated measurements, the recovery of IB in Ibalgin® sample varied between 86 ± 14 and 119 ± 22%, while the unmodified GCE suffered significant interferences from the tablet components. Determination of IB in Brufen® sample was not very successful because the interference caused by sodium dodecyl sulphate. The study has shown how effectively GCE's properties can be tailored by simple adjusting of activation CV parameters.