▎ 摘　　要

Methods that can directly and sensitively quantify a set of correlative substances lack of chromophores in pharmaceuticals are persistently desired. Here, by facile preparation of Pt-Pd nanoparticles/chitosan/nitrogendoped graphene (N-Gra) nanocomposite, we establish an electroanalytical method for simultaneous detection of ascorbic acid (AA), sulfite and oxalic acid (OA) that are closely involved with Vitamin C injection, a widely-used clinical drug. One-step electrodeposition of Pt-Pd bimetallic nanoparticles on chitosan/N-Gra decorated glassy carbon electrode was proposed to construct a well-performing electrocatalyst possessing notable electrochemical activity to the electrooxidation of both sulfite and OA. The electrocatalytic ability was evidenced by the increased current response and decreased oxidation overpotential. More importantly, sufficiently electrochemical resolution of multiple oxidative peaks allowed simultaneous quantitation of the three species of interest. The peak currents measured by differential pulse voltammetry were linear to the analytical concentration of AA, sulfite, and OA, yielding good linear ranges of 2 - 400 mu M, 8 - 600 mu M, and 1.5 - 500 mu M, respectively. Correspondingly, the limit of detection was 0.97 mu M, 5.5 mu M, and 0.84 mu M. This work opens a vista for multiplex assays of pharmaceuticals, including drug principal ingredient, toxic preservative, and decomposed impurity without chromatographic separation, and thus holds promise for the overall quality control for clinical drug.