The use of boronate affinity chromatography for separation of nucleic acid components and carbohydrates was first reported by Weith and colleagues in 1970 (1). Since then, the specificity of boronate has been exploited for the separation of a wide variety of cis-diol-containing compounds, including catechols, nucleosides, nucleotides, nucleic acids, carbohydrates, glycoproteins, and enzymes (2) (see Note 1). The basic interaction for boronate chromatography is esterification between boronate ligands and cis-diols. The major structural requirement for boronate/cis-diol esterification is that the two hydroxyl groups of a diol should be on adjacent carbon atoms and in an approximately coplanar configuration, that is, a 1,2-cis-diol. Although interaction of boronate with 1,3-cis-diols and trident interactions with cis-inositol or triethanolamine can also occur, 1,2-cis-diols give the strongest boronate ester bonds (3). In aqueous solution, under basic conditions, boronate, which normally has a trigonal coplanar geometry, is hydroxylated, yielding a tetrahedral boronate anion, which can then form esters with cis-diols (Fig. 1). The resulting cyclic diester can be hydrolyzed under acidic conditions, reversing the reaction. The boronate diester bond strength has not been well studied and only a few dissociation constants for phenylboronic acid diesters have been reported. Those reported include adonitol, 2.2 × 10^-3 M; dulcitol, 1.1 × 10^-3 M (4); mannitol, 3.3 × 10^-3 M (5); and NADH, 5.9 × 10^-3 M (6). The dissociation constant of 4-(N-methyl)-carboxamido-benzeneboronic acid and D-fructose diester is 1.2 × 10^-4 M (7). These dissociation constants are relatively high compared to the constants of 10^-4–10^-8M observed in most affinity ligand/protein interactions.