Ahmad H. Alghamdi

Electrochemical Studies and Square‐Wave Adsorptive Stripping Voltammetry of Spironolactone Drug

Abstract A sensitive and reliable stripping voltammetric method was developed to determine Spironolactone drug. This method is based on the adsorptive accumulation of the drug at a hanging mercury drop electrode and then a negative sweep was initiated, which yield a well defined cathodic peak at −1000 mV versus Ag/AgCl reference electrode. To achieve high sensitivity, various experimental and instrumental variables were investigated such as supporting electrolyte, pH, accumulation time and potential, drug concentration, scan rate, frequency, pulse amplitude, convection rate and working electrode area. The monitored adsorptive current was directly proportional to the concentration of Spironolactone and it shows a linear response in the range from 1×10−8 to 2.5×10−7 mol l−1 (correlation coefficient=0.999) and the detection limit (S/N=3) is 1.72×10−10 mol l−1 at an accumulation time of 90 sec. The developed AdSV procedure shows a good reproducibility, the relative standard deviation RSD% (n=8) at a concentration level of 1.5×10−7 mol l−1 was 1.4%, whereas the method accuracy was indicated via the mean recovery of 97.5%±2.04. Possible interferences by several substances usually present in the pharmaceutical formulations have been also evaluated. The applicability of this approach was illustrated by the determination of Spironolactone in pharmaceutical preparation and biological fluids such as serum and urine.

Square-wave adsorptive stripping voltammetric determination of an antihistamine drug astemizole

The square-wave voltammetric technique was used to explore the adsorption properties of the astemizole drug. The analytical methodology used was based on the adsorptive preconcentration of the drug on a hanging mercury drop electrode (HMDE), followed by the electrochemical reduction process which yielded a well-defined cathodic peak at −1.184 V (vs. the Ag/AgCl electrode). To achieve high sensitivity, various experimental and instrumental variables were investigated such as the supporting electrolyte, pH, accumulation time and potential, drug concentration, scan rate, SW frequency, pulse amplitude, convection rate, and the working electrode area. Under the optimized conditions, the AdSV peak current was proportional over the analyte concentration range of 5 × 10−7 to 2.5 × 10−6 mol L−1 (r = 0.998) with the detection limit of 1.4 × 10−8 mol L−1 (6.4 ng mL−1). The precision of the proposed method in terms of RSD was 2.4 %, whereas the method accuracy was indicated by the mean recovery of 100.1 %. Possible interferences of several substances usually present in the pharmaceutical tablets and formulations were also evaluated. The applicability of this electroanalytic approach was illustrated by the determination of astemizole in tablets and biological fluids.