Collaborative study of the determination of cloxacillin by column liquid chromatography

A previously published column liquid chromatographic method proposed for the analysis of cloxacillin preparations was subjected to an interlaboratory collaborative study. The method is rigorously defined in terms of performance requirements, yet allows a degree of flexibility to the individual analyst. Eight participating laboratories submitted results for the analysis of three samples in duplicate. The data from one laboratory were rejected because they failed to meet the prescribed performance criteria. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations of the results of the analysis of cloxacillin preparations. were found to be less titan 0.65% and 1.33%, respectively.