Glassy carbon electrode modified with a film of Nanodiamond-graphite/chitosan:Application to highly sensitive electrochemical determination of Azathioprine

A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan (NDG/Cs/GCE) is constructed for the first time and is used to simple and highly sensitive voltammetric determination of azathioprine (Aza). The surface morphology of the film modifier and its thickness are characterized using atomic force microscopy. The electrochemical response characteristics of the modified electrode toward Aza are investigated by means of the cyclic voltammetry (CV). The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in its reduction overpotential (~ 232 mV) and enhancement of the kinetics of the electrode reaction with a significant increase of the peak current (~ 70 times). The effects of the experimental variables, such as the deposited amount of nanodiamond-graphite/chitosan suspension, the pH of the supporting electrolyte, the accumulation potential and time, as well as the potential scan rate are investigated. Under the optimal conditions, the modified electrode showed a wide linear response to the concentration of Aza in the range of 0.2–100 μM with a detection limit of 65 nM. The prepared modified electrode showed several advantages such as simple preparation method, high stability and uniformity in the composite film, high sensitivity, excellent catalytic activity in physiological conditions and good reproducibility. The modified electrode is successfully applied for the accurate determination of trace amounts of Aza in pharmaceutical and clinical preparations with satisfactory results.

Keywords:

Azathioprine , Nanodiamond-graphite , Chitosan , Modified electrode , Cyclic voltammetry