Determination of Dicloxacillin Preparations by Liquid Chromatography

A reversed-phase liquid chromatographic method was developed for the assey of dlcloxaclllln In bulk drugs and pharmaceutical praparatlons. The samples were analyzed on a µ-Bondapak (C18) column with a mobile phase of methanol-4% acetic acid (60 + 40) at a flow rate of 1.5 Ml/min, with UV absorbance detection at 254 nm. An equation was derived showing a linear relationship between peak area ratios of dlcloxaclllln to dlmethylphthalate (Internal standard) and the dlcloxaclllln concentration over a range of 2-30µg (r = 0.9999). Standard addltlon recoveries ranged from 98.65 to 100.74% (mean 99.70%, n = 6). The coefficient of variation was less than 0.24%. The assay results were compared with those obtained by the official microbiological method, which Indicated that the proposed method. Is a suitable substitute for the microbiological method for potency assays and stability studies of dlcloxaclllln preparations.