Determination of macrolide antibiotics by liquid chromatography

The liquid chromatographic separation of seven macrolides used in food producing animals in the European Union has been studied. Separation was performed by using an end-capped high-purity silica-based C18 column and mobile phases consisting of phosphate buffer (pH 2.5)-acetonitrile mixtures. The effect of pH and acetonitrile percentage on the separation was examined. Two UV-based detection systems, wavelength programming and diode array, were assayed. Detection limits were in the range 6-33 microg l(-1) for spiramycin, tilmicosin, tylosin, kitasamicin and josamicin and about 400 microg l(-1) for erythromycin and oleandomycin. The suitability of the method for multiresidue determination of the five macrolides is demonstrated by the analysis of spiked samples of chicken muscle.