ION-EXCHANGE CHROMATOGRAPHY OF LACTOSE-LACTULOSE ISOMERIZATION MIXTURES USING A BORIC ACID BORATE ELUENT

Mixtures obtained by the isomerization of lactose on anion exchangers have been analysed by ion-exchange chromatography. With a 57-mm column of Aminex A-25 and 0.400 M H3BO3-0.005 M Na2B4O7 as eluent, a complete separation of actose, epilactose (4-O-β-d-galactopyranosyl-d-mannose), lactulose, galactose and tagatose is obtained in about 50 min. The influence of various factors on the qualitative and quantitative results is given. The ratio of Na2B4O7 to H3BO3 in the eluent has an important influence on the order of elution of ketoses and aldoses, especially at low ratios. A special device is described for removing excess of lactose during the analysis. The method describe is also applicable to the analysis of lactulose syrups. © 1979.