Abstract
A simple colorimetric procedure is described for the quantitation of ampicillin and amoxicillin in their pharmaceutical preparations. The color production is based on the reaction of the oxidation product of ascorbic acid, dehydroascorbic acid, with the corresponding penicillenic acids obtained by the degradation of the antibiotics after heating under acidic conditions. The reaction demonstrated selectivity towards the penicillins having amino acid side chains and thus allowed interference-free quantitation of ampicillin and amoxicillin in combination with cloxacillin or clavulenic acid. The procedure showed good accuracy and precision and offers advantages over the official and many other reported analytical procedures.