Capillary electrophoresis coupled to electrospray mass spectrometry through a coaxial sheath flow interface and semi-permanent phospholipid coating for the determination of oligosaccharides labeled with 1-aminopyrene-3,6,8-trisulfonic acid.

For the first time, a semi-permanent phospholipid coating is utilized in capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS). Although phospholipids in free solution are generally avoided in ESI, they did not interfere with the detection of linear and branched oligosaccharides using ESI operated in negative mode. The CE and ESI were coupled using a coaxial sheath flow interface. The separation was operated in reversed polarity and the electroosmotic flow was effectively suppressed by the phospholipid coating. The method was characterized with linear oligosaccharides and used to monitor the enzymatic hydrolysis of maltooligosaccharides with α-amyloglucosidase. Branched oligosaccharides were separated and detected with the system. The enzyme β1-4 galactosidase was used to distinguish branched isomeric oligosaccharides derived from asialofetuin.