Voltammetric determination of sumatriptan based on a graphene/gold nanoparticles/Nafion composite modified glassy carbon electrode.

A mixture of graphene oxide and tetrachloroauric acid was electrochemically co-reduced directly on a glassy carbon electrode (GCE) surface via cyclic voltammetry so as to form a graphene (Gr)-gold nanoparticles (AuNP) composite. This nanocomposite was then coated with nafion (NAF) film so as to form Gr/AuNP/NAF/GCE. Sumatriptan (SUM) is a drug belonging to the triptan class, used for the treatment of migraine headaches. In this work, an electrochemical method based on the adsorptive stripping differential pulse voltammetry (AdSDPV) employing Gr/AuNP/NAF/GCE has been proposed for the subnanomolar determination of SUM. Characterization of the electrode material has been carried out by UV-visible spectrophotometry, X-ray diffraction and scanning electron microscopy. Also the electrode surface has been characterized by means of cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry. By employing Gr/AuNP/NAF/GCE at pH 7.0 phosphate buffer, a 20-fold enhancement in the AdSDPV signal was observed as compared to GCE. Under the optimized conditions, Ip (µA) was proportional to the SUM concentration in the range of 1.0×10(-6)-4.12×10(-5) M (R(2)=0.9991) and 2.14×10(-9)-1.0×10(-6) M (R(2)=0.9954) with a detection limit (3×SD/s) of 7.03×10(-10) M. The practical analytical utilities of the modified electrode were demonstrated by the determination of SUM in pharmaceutical formulations, human urine and blood serum samples. This proposed method was validated by HPLC and the results are in agreement at the 95% confidence level.