Determination of methylprednisolone acetate in biological fluids at gold nanoparticles modified ITO electrode

The electrochemical behavior of a corticosteroid methylprednisolone (MP), used for doping, has been studied at gold nanoparticles modified indium tin oxide (nanoAu/ITO) electrode. The nanoAu/ITO electrode exhibited an effective catalytic response towards its oxidation and lowered its oxidation potential by ∼127 mV when compared with bare ITO electrode. Oxidation of MP has been carried out in phosphate containing electrolyte in the pH range 2.13–10.00 and a well-defined oxidation peak was noticed. Linear concentration curves are obtained over the concentration range 0.01–1.0 μM with a detection limit of 2.68 × 10−7 M at nanoAu/ITO electrode. A diffusion coefficient of 2.36 × 10−6 cm2/s is calculated for MP using chronoamperometry. The proposed method is effectively applied to detect the concentration of MP in pharmaceutical formulations and human blood plasma and urine samples. A comparison of MP concentration determined in blood plasma and urine by the proposed method and GC/MS indicated that the results are essentially similar. It is believed that the method will be useful in determining this drug in case of doping.