PREPARATIVE LIQUID-CHROMATOGRAPHY FOR MAC ROLIDE ANTIBIOTICS

To develop the design procedure for preparative liquid chromatography of macrolide antibiotics, parameters for the adsorption isotherms and for the ralated rate processes were estimated experimentally and the m easured and calculated chromatograms were compared. Erythromycin and e rythromycin ethyl succinate were selected as a representative antibiot ic and a model impurity, respectively. Parameters in Langmuir type ads orption isotherms and rate parameters for silica gel-organic solvent s ystems were obtained from the values of the moments for the single com ponent chromatograms. Parameters for the adsorption isotherms showed t hat the extent of separation between solutes varied greatly with the k ind and composition of the mobile phase. The mass transfer coefficient s in the stationary and mobile phases were compared with the previous correlations. Binary chromatograms were calculated numerically with th e use of Markham-Benton type isotherms for the binary solutes and the values of the said parameters. The calculated and measured chromatogra ms agreed fairly well over all operating conditions. In conclusion, it was recommended for the design of preparative liquid chromatography t o calculate chromatograms of macrolide antibiotics by use of parameter s estimated by the method presented here.