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
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.