Carbohydrates guard columns

Every analysis performed on columns of this type (for example, carbohydrates, alcohols, organic acids, mixtures of these) can be improved with a column in the most suitable ionic form, even though solutions with compounds of differing types may impose the choice of a compromise. In analytical practice, however, it is not advisable to make an in-column conversion from one form to another, for the resin could shrink or even swell in relation to the type of cation linked. The effect of fixed-cation is made obvious when the compounds under analysis can coordinate with it, as in the case of carbohydrates. For example, the linkage of sugars with three adjacent hydroxyls may be more stable than those that have only two, with obvious effects in the resolution of the analytes. Finally, it is advisable to use a guard column to prolong the life of the... 

Figure 3 Hydroxyapatite chromatography of serum glycoproteins on a spherical hydroxyapatite column (0.75 x 10 cm, Toa Nenryo K.K., Tokyo), with guard column. The column was eluted at a flow rate of 0.8mL/min for 60 min with a linear gradient from 0.01 M sodium phosphate buffer, pH 6.8, containing 0.3 mM CaClg to 0.5 M sodium phosphate buffer, pH 6.8, containing 0.01 mM CaCl2. The abbreviations in Fig. 2 are used. The following abbreviations are used in the chromatogram of ceruloplasmin Apo, apoceruloplasmin I, carbohydrate variant type I II, carbohydrate variant type II. A sample up to 20 mg could be applied without any loss of resolution.

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