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Analytical application of acetate anion in negative electrospray ionization mass spectrometry for the analysis of triterpenoid saponins–ginsenosides
Author(s) -
Ng KwanMing,
Che ChiMing,
Wo SiuKwan,
Tam Paul KwongHang,
Lau Allan SikYin
Publication year - 2006
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2465
Subject(s) - chemistry , glycosyl , electrospray ionization , disaccharide , ammonium acetate , mass spectrometry , ginsenoside , trisaccharide , monosaccharide , ethyl acetate , stereochemistry , chromatography , medicinal chemistry , ginseng , organic chemistry , high performance liquid chromatography , medicine , alternative medicine , pathology
Ginsenosides containing different numbers of glycosyl groups can be easily differentiated based on the formation of characteristic ginsenoside‐acetate adduct anions and deprotonated ginsenosides generated by electrospray ionization (ESI) of methanolic solutions of ginsenosides (M) and ammonium acetate (NH 4 OAc). Ginsenosides containing two glycosyl groups gave a characteristic mass spectral pattern consisting of [M+2OAc] 2− , [M−H+OAc] 2− and [M−2H] 2− ions with m/z values differing by 30 Th, while this mass spectral pattern was not observed for ginsenosides containing one glycosyl group. Formation of [M+2OAc] 2− was influenced by the chain length of glycosyl groups and was used to differentiate the ginsenosides containing different combinations of monosaccharide and disaccharide units in the glycosyl groups. Under identical collisional activation conditions, [M+OAc] − , [M−H+OAc] 2− and [M+2OAc] 2− underwent proton abstractions predominantly to generate [M−H] − , [M−2H] 2− and [M−H+OAc] 2− ions, respectively. The ion intensity ratios, I [M−H] −/I [M+OAc] −, I [M−2H] 2−/I [M−H+2OAc] 2−and I [M−H+OAc] 2−/I [M+OAc] 2−, being sensitive to the structural differences of ginsenosides, could differentiate the isomeric ginsenosides, including (i) Rf, F 11 and Rg 1 , (ii) Rd and Re, and (iii) Rb 2 and Rc. Additionally, NH 4 OAc was found to enhance the sensitivity of detection of ginsenosides in the form of [M−H] − down to the femtomole level. Copyright © 2006 John Wiley & Sons, Ltd.