Liquid chromatographic determination of erythromycins in fermentation broth

A simple and sensitive isocratic LC method is described for the determination of erythromycins in fermentation broths. A simple technique utilizing acetone-methyl ethyl ketone, 1:1, as extraction solvent was coupled with suitable chromatographic conditions - compounds were separated on a 250 mm x 4.6 mm i.d., 5 mum, reversed-phase column at 65 degreesC with acetonitrile-0.2 M K2HPO4 pH 7.0-water, 35:5:60 (v/v), as mobile phase at a flow rate of 1.0 mL min(-1). UV detection was performed at 215 nm. Separation of erythromycin F from polar components of the fermentation liquid was sufficient. Erythromycins A, B, C, D, and E, and N-desmethylerythromycin A were also separated, as were known decomposition products of erythromycin A and several unknown components. The method is suitable for monitoring the progress of erythromycin fermentation.