Electrochemical studies and square-wave adsorptive stripping voltammetry of spironolactone drug

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 -1000mV 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 x 10(-8) to 2.5 x 10(-7) mol 1(-1) (correlation coefficient=0.999) and the detection limit (S/N=3) is 1.72 x 10(-10) mol 1(-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 x 10(-7) mol 1(-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.