ADSORPTIVE STRIPPING VOLTAMMETRIC DETERMINATION OF TETRACYCLINE AND OXYTETRACYCLINE

A sensitive voltammetric method is developed for the quantitation of the antibiotics tetracycline and oxytetracycline (Terramycin). The method is based on controlled adsorptive preconcentration of the antibiotic on the hanging mercury drop electrode (HMDE), followed by tracing the voltammogram in a cathodic potential scan. The modes used are direct current stripping voltammetry (DCSV) and differential pulse stripping voltammetry (DPSV). The adsorptive stripping response was evaluated with respect to preconcentration time and potential, concentration dependence and composition of supporting electrolyte. The detection limits found were 5 x 10(-8) M (2 min. preconcentration) by DPSV and 1 x 10(-7) M (10 sec.) by DCSV. These values correspond to 25 and 50 ppb respectively. The relative standard deviation (at 1 x 10(-7) M level) is 1.4%. Successful applications of the method to analysis of urine and pharmaceutical formulations as capsules or ampules, are described.