Sensitive electrochemical determination of epinephrine at poly(L-aspartic acid)/electro-chemically reduced graphene oxide modified electrode by square wave voltammetry in pharmaceutics

A simple and sensitive poly(L-aspartic acid)/electrochemically reduced graphene oxide modified glassy carbon electrode, P(L-Asp)/ERGO/GCE, was constructed by electrochemical reduction of GO drop coated on glassy carbon electrode within 2 mM L-aspartic acid by cyclic voltammetry in pH 6 PBS which give rise to in situ polymerization of L-aspartic acid on electrochemically reduced graphene oxide. Raman, FTIR and UV spectroscopy were used to characterize GO, ERGO, P(L-Asp) and P(L-Asp)/ERGO composites. The P(L-Asp)/ERGO/GCE was used for epinephrine (EP) detection using square wave voltammetry. The electrochemical response of P(L-Asp)/ERGO/GCE was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and electroactive surface area (ESA) measurements. A significant enhancement in the peak current response of EP was observed accompanied with a negative shift in peak potential at the composite modified electrode compared to the bare electrode. The prepared P(L-Asp)/ERGO/GCE exhibited excellent SWV response towards EP detection in the range of 0.1-110 mu M with limit of detection and quantification of 0.025 and 0.083 mu M, respectively. Real sample analysis was carried out in pharmaceutical formulation of EP hydrochloride injection, which revealed good recovery results, 94-109%. The method was further validated by the UV assay and the obtained result confirmed the applicability of the present method for routine analysis. The proposed sensor also displayed good selectivity, repeatability and reproducibility with appreciable long-term stability.