PREPARATIVE SEPARATION OF BITTER ACIDS FROM HOP EXTRACTS BY CENTRIFUGAL PARTITION CHROMATOGRAPHY

Centrifugal partition chromatography was used for preparative separati on of alpha- and beta- bitter acids from a crude supercritical carbon dioxide extract of hop cones. A one-step gradient was applied; after e lution of the alpha-acids in the system toluene-0.1 M triethanolamine- HCl pH 8.4 in water the aqueous mobile phase was changed to 0.2 M diet hanolamine-PO4 pH 9.75 in water-methanol (4:1, v/v) for elution of the beta-acids. For the alpha-acids the yield/cost ratio was optimized th rough sample size and injection volume. The role of pK(2) values and h ydrophobicity in the separation mechanism for the alpha-acids is discu ssed. The elution order differs from the order predicted after measure ment of the partition coefficients.