Voltammetric determination of immunosuppressive agent, azathioprine, by using a graphene-chitosan modified-glassy carbon electrode

Electrodeposition of graphene-chitosan (GR-CS) composite onto glassy carbon electrode was done via a simple one-step strategy. Different methods were used for surface characterization which confirmed the presence of a nano-structure of graphene sheets. The modified electrode was highly efficient in azathioprine analysis by square-wave voltammetry. Reversibility of the redox couple of azathioprine was significantly improved at the surface of GR-CS modified electrode compared to the bare electrode. A linear range of 1.0 × 10−7 to 2.6 × 10−5 M of azathioprine was obtained with a sensitivity of 5.54 A/M and a detection limit of 4.7 × 10−8 M. The proposed sensor exhibited high reproducibility (RSD % = 5%) and repeatability (RSD % = 3.5%) and long-term storage stability. The modified electrode was applied successfully to the accurate determination of azathioprine in pharmaceutical and blood serum samples.