Purification of 2-aminopyridine derivatives of oligosaccharides and related compounds by cation-exchange chromatography.

A simple method for efficient removal of a large excess of 2-aminopyridine from the reaction mixture of pyridylamination of carbohydrates and related compounds by cation-exchange chromatography is presented. The method is especially suitable for purification and separation of small-sized pyridylaminated-(PA-) derivatives and large-scale preparations. Separation of PA-derivatives from 2-aminopyridine was accomplished by a Dowex 50X8 column (NH+4-form) eluted with 20 mM ammonium acetate buffer (pH 8.5). The PA derivatives thus purified can be used for high-performance liquid chromatography analysis directly. The method requires only 10 min to purify a sample, in contrast to an hour or longer required by the gel filtration method. Unlike the existing methods for purification method. Unlike the existing methods for purification of PA-oligosaccharides, which are applicable only in the range of 0.05-100 nmol, the cation-exchange method allows processing of much larger quantities of PA-derivatives. For example, PA-L-glyceraldehyde (10 mumol) was successful purified by a Dowex 50X8 column (1.5 x 17 cm) eluted with 20 mM ammonium acetate buffer (pH 8.75) within 3 h.