Prevention of Anomer Separation

After reduction of the sugar and saccharide, the terminal groups may have various types of cyclic forms in addition to the open-chain form. In such cases, these saccharides exist as two diastereomers because the carbon atom of the terminal reducing group is asymmetric; these diastereomers are called anomers (alpha- and beta-anomers respectively). Under certain conditions where the rate of conversion of such diastereomers is low, alpha-anomer and beta-anomer are separated as they pass through the column. This causes a undesirable splitting or broadening of the peak. For the analysis of sugars, therefore, it is necessary to prevent the anomer separation. Below are possible methods for controlling this separation:

1) It has been reported that the anomer separation does not take place at high temperature. Therefore, when using SUGAR series (SP0810, SC1011, SC1211 or KS-800), set up the column temperature at 70 to 80deg-C.
2) It has been reported that the anomer separation does not take place under strong alkaline conditions. Polymer-base columns such as NH2P allow the separation of saccharides without causing the anomer separation as the column can be used under alkaline environment.
3) For other columns, refer to the conditions described in the chromatograms.