title: Improved liquid chromatography-MS/MS of heparan sulfate oligosaccharides via chip-based pulsed makeup flow.
abstract: Microfluidic chip-based hydrophilic interaction chromatography (HILIC) is a useful separation system for liquid chromatography-mass spectrometry (LC-MS) in compositional profiling of heparan sulfate (HS) oligosaccharides; however, ions observed using HILIC LC-MS are low in charge. Tandem MS of HS oligosaccharide ions with low charge results in undesirable losses of SO(3) from precursor ions during collision induced dissociation. One solution is to add metal cations to stabilize sulfate groups. Another is to add a nonvolatile, polar compound such as sulfolane, a molecule known to supercharge proteins, to produce a similar effect for oligosaccharides. We demonstrate use of a novel pulsed makeup flow (MUF) HPLC-chip. The chip enables controlled application of additives during specified chromatographic time windows and thus minimizes the extent to which nonvolatile additives build up in the ion source. The pulsed MUF system was applied to LC-MS/MS of HS oligosaccharides. Metal cations and sulfolane were tested as additives. The most promising results were obtained for sulfolane, for which supercharging of the oligosaccharide ions increased their signal strengths relative to controls. Tandem MS of these supercharged precursor ions showed decreased abundances of product ions from sulfate losses yet more abundant product ions from backbone cleavages.
authors.affiliation: Center for Biomedical Mass Spectrometry, Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Shi
authors.forename: Xiang
authors.initials: X
authors.lastname: Yu
authors.forename: Nancy
authors.initials: N
authors.lastname: Leymarie
authors.forename: Gregory O
authors.initials: GO
authors.lastname: Staples
authors.forename: Hongfeng
authors.initials: H
authors.lastname: Yin
authors.forename: Kevin
authors.initials: K
authors.lastname: Killeen
authors.forename: Joseph
authors.initials: J
authors.lastname: Zaia
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D006497:Heparan Sulfate / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013876:Thiophenes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006497:Heparan Sulfate; D009844:Oligosaccharides; D011506:Proteins; D013876:Thiophenes; C013693:sulfolane