Balance of xanthophylls molecular and protonated molecular ions in electrospray ionization.
This paper reports the chemical evidence of the balance between radical molecular ions and protonatedmolecules of xanthophylls (an oxygen-containing carotenoid) with a conjugated pi-system (polyene) and oxygen as a heteroatom in ESI and HRESI mass spectrometry. The ionization energy of neutral xanthophylls was calculated by semi-empirical methods. The results were compared with those previously published for carotenoids and retinoids, which have also been shown in ESI-MS to form M(+*) and [M + H](+), respectively. This study demonstrates, for the first time, the correlation of an extended conjugation and the presence of oxygen in the formation and balance of M(+*) or [M + H](+) for the carotenoids, neoxanthin, lutein, violaxanthin and zeaxanthin.
Guaratini
Thais
T
Universidade de São Paulo, Instituto de Química, Departamento de Bioquímica, Av Professor Lineu Prestes, 748 CP 20780, CEP 05508900, São Paulo-SP, Brazil.
Vessecchi
Ricardo
R
Pinto
Ernani
E
Colepicolo
Pio
P
Lopes
Norberto P
NP
D007477:Ions / Q000737:chemistry; D014975:Lutein / Q000737:chemistry; D015394:Molecular Structure; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D024341:Xanthophylls / Q000096:biosynthesis / Q000737:chemistry*; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives / Q000737:chemistry
D007477:Ions; D011522:Protons; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; C031140:antheraxanthin; C005613:violaxanthin; C011947:neoxanthin; D014975:Lutein