Preliminary study of the analysis of oligogalacturonic acids by electrospray ionization mass spectrometry

During systematic studies of the behavior of oligogalacturonic acids (OGAs) under different conditions using electrospray ionization mass spectrometry (ESI-MS), cation adduction, fragmentation and non-covalent binding were found to be the three major problems that compromised the analysis of OGAs by ESI-MS. By adjusting solution components, capillary temperature and capillary voltage in the ESI source, an optimized condition was found that gave a clean and clear spectrum of trigalacturonic acid. A direct injection ESI-MS technique based on the use of aqueous acetonitrile and acetic acid and triethylamine (TEA) as modifiers has been applied to analyze a mixture including mono-, di- and trigalacturonic acids, which will facilitate further applications of ESI-MS in the analysis of mixtures of OGAs.