ABSTRACT
A sensitive and reliable stripping voltammetric method was developed to determine chlorotetracycline drug. This method is based on the adsorptive accumulation of the complex of this drug with Zn [II] at a hanging mercury drop electrode and then a negative sweep was initiated, which yield a well defined cathodic peak at - 928 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, scan rate, frequency, pulse amplitude, convection rate and working electrode area. The monitored adsorptive current was directly proportional to the concentration of chlorotetracycline and it shows a linear response in the range from 1 x 10[-7] to 1.4 x 10[-6] mol 1[-1] of chlorotetracycline [correlation coefficient = 0.999] and the detection limit [S/N=3] is 7.2 x 10[-9] mol 1[-1] at an accumulation time of 40 sec. The developed AdSV procedure shows a good reproducibility, the relative standard deviation RSD% [n=8] at a concentration level of 5 x 10[-7] mol 1[-1] of chlorotetracycline and 1 x 10[-6] mol 1[-1] of Zn[++] was 3.4%, whereas the method accuracy was indicated via the mean recovery of 99% +/- 1.0. 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 the chlorotetracycline in pharmaceutical preparation and biological fluids such as serum and urine