Simultaneous determination of ampicillin and cloxacillin in presence of their degradation products, either in binary mixtures or in pharmaceutical formulations

A simple liquied chromatographic method for the simultaneous determination of ampicillin and cloxacillin in drug formulations is presented. The method could be applied for the determination of the two drug substsnces in presence of their degradation products without apparent interferences. The LC-sparation was undertaken on a reversed phase 100 RP-18 Lic hrospher [5 micro m] column using a mobile phase of acetonitrile and 1% acetic acid, 51:49, v/v at a rate of 1.8 ml/min with UV detection at 240 nm. The suitability of the LC-system developed, as tested by replicate injections of the sample and standard preparations, gave relative standard deviations [RSD[S]] less than 2%. The statistical evaluations of the results of the assay and recovery experiments indicated good accuracy of the proposed LC-method

Analysis of pharmaceutical formulations containing ampicillin and cloxacillin using second-derivative spectroscopy on a diose-array spectrophotometer

Two-component mixture of ampicillin and cloxacillin with considerable overlapping spectra was assayed by a second-derivative spectrophotometric method using a diode-array spectrophotometer. The second-derivative spectra of sample solutions in distilled water were scanned between 260 and 300 nm. Derivative measurements were carried out at 269 nm [zero-crossing], and at 288 nm [peak-to-zero] for ampicillin and cloxacillin, respectively. The procedure does not require any separation step or chemical reagents and allows for a single-unit assay for normal dosage used. Beer's law holds up to 14 mg% for both penicillins. The method was successfully applied to commercial preparations containing a binary mixture of both penicillins