A new electrochemical paper platform for detection of 8-hydroxyquinoline in cosmetics using a cobalt phthalocyanine-modified screen-printed carbon electrode

An electrochemical paper-based analytical device (ePAD) using an electrocatalytic cobalt(II) phthalocyanine-modified screen-printed carbon electrode (CoPc-SPCE) was first developed for the determination of 8-hydroxyquinoline (8-HQ). The electrochemical behavior of 8-HQ on the CoPc-modified electrode was investigated by cyclic voltammetry (CV) and square-wave voltammetry (SWV). The obtained results demonstrated that the CoPc-SPCE shows high electrocatalytic activity toward the oxidation of 8-HQ. The oxidation potential was shifted to a negative value compared to those obtained from the unmodified electrode. Under the optimized experimental conditions, a good linear relationship between the 8-HQ concentration and the peak current was obtained within the range of 10-250 mu M with a detection limit of 0.89 mu M. Furthermore, the method was successfully applied for the determination of 8-HQ in cosmetic samples. According to a paired t-test, the results were in good agreement with results from the standard HPLC-UV method. The benefits of this proposed device are that it is easily fabricated, low cost, disposable, highly sensitive and reproducible.