Borate is a known contaminant in laboratory water supplies. In chromatography, borate contamination of chromatography eluents may be a result of degrading deionized water systems or as leachate from borosilicate glassware. Borate contamination in eluents can cause a significant loss of peak efficiency, especially for mannose, fructose, and reduced monosaccharides. If borate is present in the eluent, it binds both to the anion-exchange column and to the carbohydrate analytes. The carbohydrate-borate complex is less efficiently eluted from the anion-exchanger than is the carbohydrate, resulting in peak tailing, particularly where vicinal cis hydroxyl groups are present, such as for mannose and sugar alcohols.