Determination of nimesulide in human serum using a glassy carbon electrode modified with SiC nanoparticles

A glassy carbon electrode (GCE) was modified with silicon carbide nanoparticles and used to investigate the electrochemistry of the drug nimesulide via voltammetry and chronoamperometry. The structure of the modified electrode was studied by field emission scanning electron microscopy. Nimesulide undergoes electroreduction at pH 2 at a potential that is shifted from -526 mV (at the bare GCE) to -387 mV at the modified electrode. Simultaneously, sensitivity is increased by a factor of 5.8. The charge transfer coefficient, diffusion coefficient, standard heterogeneous rate constant and catalytic reaction rate constant were determined. A plot potential vs. pH revealed a voltammetric pKa value of about 6.5-7.0. The differential pulse voltammetric calibration plot for nimesulide is linear in 0.09-8.7 μM concentration range, and the detection limit and sensitivity are 30 nM and 512 nA.μM-1, respectively. The modified electrode was applied to the determination of nimesulide in acidic solution and human blood serum samples without further pretreatment. The recoveries, as determined by the standard addition method, range from 95.7 to 98.7%, with an RSD of around 1.6%. (author)