Spectrophotometric determination of ampicillin, dicluxacillin, flucloxacillin and amoxicillin antibiotic drugs: ion-pair formation with molybdenum and thiocyanate.

A sensitive spectrophotometric method is developed for the determination of some antibiotic drugs such as ampicillin (amp), dicluxacillin (dicl), flucloxacillin (fluc) and amoxicillin (amox). The method involves the formation of ion-pairs between these drugs under investigation and inorganic complex of Mo (V) thiocyanate followed by its extraction with methylene chloride. The optimum conditions for the ion-pairs formation are established. The method permits the determination of amp, dicl, fluc and amox over a concentration range of 1.5-77.5, 3-75, 1.5-79 and 7.5-75 microg ml(-1) respectively. The sensitivity (S) is found to be 0.017, 0.061, 0.014 and 0.073 microg cm(-2) for amp, dicl, fluc and amox, respectively. The method is simple, rapid, reproducible and accurate within +/- 1%. The method is applicable for the assay of the four drugs under investigation in different dosage forms and the results are in good agreement with those obtained by the official method.