A new colorimetric method for the assay of erythromycin.

A chemical assay method which depends upon the development of intense absorption at 485 nm has been found satisfactory for the assay of erythromycin and its stearate from tablets, suspensions and other preparations. Its utility is brevokable for the determination of this antibiotic at all stages of manufacture, process and formulation, and it is more rapid and reproducible than the bioassay (JPMA 33:256, 1983).