ANALYSIS OF LINEAR OLIGOGALACTURONIC ACIDS BY NEGATIVE-ION ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

Linear oligogalacturonic acids (1,4-linked alpha-D-galacturonic acid o ligomers), obtained by partial acid hydrolysis of orange polygalacturo nides, were studied by negative-ion electrospray ionization mass spect rometry, without prior sample derivatization. After preparative separa tion using high-resolution anion-exchange chromatography, some fractio ns enriched in uronic acids were desalted, transferred into a methanol + water solution adjusted to pH 10, and directly submitted to electro spray ionization mass spectrometry in the negative-ion recording mode. Clear molecular mass assignments of the oligomers, covering a degree of polymerization between 4 and 7, were obtained.