Determination of Penicillins in pure form and in Pharmaceuticals

Abstract

A rapid and convenient method is described for the determination of thirteen commercially available penicillins: methicillin Na, oxacillin Na, cloxacillin Na, dicloxacillin Na, nafcillin Na, ampicillin Na, amoxicillin, carbenicillin Na, penicillin-G Na, penicillin-G procain salt, penicillin-G benzathine salt, phenoxymethylpenicillinic acid K and phenoxymethylpenicillinic acid benzyl ester sulphoxide. Penicillins are esthted spectrophotowtrically, by oxidizing them under strongly acidic conditions, by means of an excessive quantity of amnonium vanadate. The mixture is heated at 180°C for 15 min and the absorbance of the colour developed is measured at 760 nm against a blank. Beer's law is followed for up to 120 μg/ml of antibiotic. The method is applied to the mlysis of various pharmaeutical preparations for these drugs.