Separation of neutral saccharide mixtures with capillary electrochromatography using hydrophilic monolithic columns

While developing a combination of capillary electrochromatography (CEC) with tandem mass spectrometry (MS) for the benefit of characterizing complex oligosaccharide mixtures, we needed highly efficient CEC columns operating in an "MS-friendly" mode. We demonstrate here novel types of polar, monolithic CEC columns that separate effectively complex mixtures of saccharides with the use of mobile phases containing acetonitrile/dilute ammonium formate buffers. Using the positive-ion mode of detection for neutral saccharides, the detection conditions were optimized down to the low-femtomole sensitivities with the use of an ion trap mass spectrometer. This column technology provides a nearly universal system that can separate a wide range of carbohydrates: mono- and oligosaccharides with the intact reducing end, as well as saccharide alditols. Even the anomers formed due to mutarotation could be resolved with a high content of organic phase.