Application of centrifugal countercurrent chromatography to the separationof macrolide antibiotic analogues. II. Determination of partition coefficients in comparison with the shake-flask method

The separation of compounds by centrifugal counter-current chromatography ( CCC) is based on the difference in partition behaviour of solutes between t he two immiscible liquid phases. Therefore, Delta log K, defined as the dif ference of partition coefficients of the solutes, is st key criterion in th e solvent system selection for the CCC. Partition coefficients (log K) of m acrolide antibiotic analogues can be measured by different ways, such as di rect shake-flask method or indirect HPLC analysis. However, there are also some clear limitations and shortcomings with these methods. As an alternati ve, a Quattro Counter-Current Chromatograph was examined to measure log K f or a series of macrolide antibiotic analogues and compared with the classic al shake-flask method. The experimental results shows that partition coeffi cients measured by CCC are highly correlated with those determined by shake -flask method. The major advantages of the CCC method are rapidity, precisi on, and the possibility to determine log K of analytes in mixtures. Therefo re, CCC is a promising alternative to directly measure the partition coeffi cients of macrolide antibiotics analogues in purification process developme nt.