Caspary

Caspary refers to a chromatographic technique, specifically a type of affinity chromatography, used primarily in carbohydrate analysis. It involves boronic acid-based stationary phases to selectively bind compounds containing cis-diol groups, such as carbohydrates and glycosylated molecules.

The underlying principle of Caspary chromatography relies on the reversible covalent interaction between a boronic acid moiety immobilized on a solid support and the vicinal diol groups present in many carbohydrates. Under alkaline conditions, boronic acids form boronate anions, which then react with the cis-diol groups of carbohydrates to form cyclic boronate esters. This interaction allows for the selective retention of carbohydrates on the column.

Elution of the retained carbohydrates is typically achieved by decreasing the pH of the mobile phase, which protonates the boronate ester, disrupting the complex and releasing the carbohydrate. Alternatively, a competitive eluent like sorbitol or other compounds with strong boronic acid affinity can be used.

Caspary chromatography is particularly useful for separating and purifying complex carbohydrate mixtures, including polysaccharides, glycoproteins, and monosaccharides. Applications include carbohydrate analysis in biological samples, food chemistry, and pharmaceutical development. The technique offers advantages such as high selectivity and the ability to separate compounds based on subtle structural differences in their carbohydrate moieties. Its use is dependent on the presence of suitable cis-diol groups within the target molecules.