Resolution of Isobaric Poly- and Phosphosaccharides Using Differential Ion Mobility Separations and Electrospray Ionization Mass Spectrometry

摘要

Differential Ion Mobility Separation enables the distinction of multiple sets of structural isomers. Increases in the separation voltage as well as increased concentrations of some dopants were seen to have a beneficial effect on isobaric separations. (1) For polysaccharide analysis, 1.5% isopropanol mixed into the buffer gas with a separation voltage of 4500 V yielded substantially improved separations over other dopants (including acetonitrile and methanol). This improvement can be seen in the 10.4 V distance between compensation voltages for (in the case of the trisaccharides) the 2.4 V wide peaks of sodiated maltotriose (7) and raffinose (6), from a 0 V separation at 1500 V. (2) Work to determine causes for peak splitting, as seen in the cases of the diastereomeric pentasaccharides (12, 13) is ongoing. (3) For phosphosaccharide analysis, the utility of separation even in cases where peaks may be incompletely resolved is clear in that MS/MS data still enables isolation of values for specific detection, as is the case for separating Glucose-1-Phosphate from Glucose-6-Phosphate.