▎ 摘　　要

A highly sensitive amperometric method is performed for determination of the pharmaceutical drug guaifenesin (GFN), which is commonly used for temporary relief from congested chest, cough and other breathing illnesses. Over dosages of GFN may cause nausea and vomiting. Hence, developing a sensor strip for rapid detection of GFN is essential. In this regard, we prepared Ni-SiO2 nanosphere-decorated multilayer graphene nanosheets (Ni-SiO2/ MLG) composite catalyst for GFN detection by probe sonication. The catalyst was characterised by X-ray diffraction, Raman spectroscopy and scanning electron microscopy analyses. Disposable screen-printed carbon electrodes (SPCE) were modified with Ni-SiO2/MLG catalyst to evaluate GFN oxidation behaviour by cyclic voltammetry and amperometry techniques. Ni-SiO2/MLG/SPCE exhibited a good linear range of detection (0.1-317.5 mu M), high sensitivity (408.88 mu A mM-1 cm-2) and low detection limit (5.7 nM). It is also exhibited high selectivity to GFN in the presence of interference molecules within the high positive potential range. Stability and reproducibility analyses indicated that the unique Ni-SiO2/MLG composite materials can be an excellent candidate to fabricate a flexible electrode for biosensing and other electrochemical applications.