Quantitative analysis of malto-oligosaccharides by MALDI-TOF mass spectrometry, capillary electrophoresis and anion exchange chromatography

The analysis of malto-oligosaccharides by MALDI-TOF mass spectrometry (MS), capillary electrophoresis (CE) and anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) is described. Appropriate methods were developed which enabled the resolution of the oligosaccharides and quantification of the peak areas. It could be shown that each technique provided a different distribution profile of the maltodextrins. Using MALDI-TOF MS signals of higher molecular weight oligomers were enhanced while low molecular weight analogues were discriminated. Thus, the response factor depends on the degree of polymerization (DP) of the carbohydrates. Homologues up to DP-15 could be detected. Analysis of the maltodextrins by CE was accomplished by derivatization of the sugars with 4-aminobenzonitrile (ABN) and 8-aminonaphthalene-1,3,6-trisulfonic acid, respectively. By using the latter reagent oligosaccharides up to DP-13 were detected while derivatization with ABN allowed detection up to DP-9. The molecular weight distribution obtained by both approaches were the same. HPAEC-PAD enabled the determination of oligomers up to DP-9. The distribution obtained by this technique showed somewhat lower signals of the small homologues than those found by CE while the opposite held for higher molecular weight compounds. Hydrolysis of the carbohydrates by the derivatization reaction prior to CE analysis, which increased the proportion of low molecular weight homologues, may account for these findings. Receiverd: 28 August 1997 / Revised: 24 November 1997 / Accepted: 25 November 1997