A simple, precise and accurate method to determine ampicillin and dicloxacillin in a pharmaceutical preparation capsule dosage form were developed and validated using liquid chromatography (LC). The LC separation was achieved on an ACE 150 mm x 4.6 mm, 5 µ in the isocratic mode using buffer: methanol (40: 60, v/v), as the mobile phase at a flow rate of 1.0 mL/min. The methods were performed at 220 nm. In LC method, quantification was achieved with PDA detection over the concentration range of 50 to150 µg/mL. The methods were validated and the results were compared statistically. They were found to be simple, accurate, precise and specific. The methods were successfully applied for the determination of ampicillin and dicloxacillin in a pharmaceutical preparation capsule dosage form without any interference from common excipients. The proposed method was validated in terms of precision, robustness, recovery, LOD and LOQ. All the validation parameters were within the acceptance range.

A simple and precise reversed phase high performance liquid chromatographic method has been developed and validated for the quantification of benzalkonium chloride (BKC) preservative in pharmaceutical formulation of latanoprost eye drops. The analyte was chromatographed on a Waters Spherisorb CN, (4.6×250 mm) column packed with particles of 5 μm. The mobile phase, optimized through an experimental design, was a 40:60 (v/v) mixture of potassium dihydrogen orthophosphate buffer (pH 5.5) and acetonitrile, pumped at a flow rate of 1.0 mL/min at maintaining column temperature at 30 °C. Maximum UV detection was achieved at 210 nm. The method was validated in terms of linearity, repeatability, intermediate precision and method accuracy. The method was shown to be robust, resisting to small deliberate changes in pH, flow rate and composition (organic ratio) of the mobile phase. The method was successfully applied for the determination of BKC in a pharmaceutical formulation of latanoprost ophthalmic solution without any interference from common excipients and drug substance. All the validation parameters were within the acceptance range, concordant to ICH guidelines.