ABSTRACT
Traditionally, the analysis of a wide variety of antibiotics, regardless of the structures and matrices involved, has been performed using microbiological assay methods. In 1945 [1], the basic protocols for antibiotic analyses were established; these protocols for inhibition or diffusion procedures remain as the basis of the analytical science involved [2]. The microbiological assay procedures, whether based upon the diffusion of turbidimetric systems, all 416suffer from a basic flaw: the procedures are nonspecific. Many of the commonly used procedures utilize only a purification by dilution prior to analysis. Also, the organisms used in the assays respond to more than one antibiotic family, as well as other nonspecific inhibitory materials. Hence there are, inherent in the microbiological assay systems, sources of analytical bias and inaccurate results. On balance, however, the sensitivity of the assay organisms to the antibiotic measured is usually sufficient to minimize many of the aforementioned problems. The lack of specificity remains a serious flaw. Reasonably elaborate separations are necessary to separate the various antibiotic families prior to analysis. This problem is not especially serious when the formulation being analyzed is known. Only in the case of unknown samples or materials of dubious lineage can this be a serious problem. This is not unique to microbial methods alone, although the problem can be acute in microbial procedures.
