Balance of xanthophylls molecular and protonated molecular ions in electrospray ionization |
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Authors: | Guaratini Thais Vessecchi Ricardo Pinto Ernani Colepicolo Pio Lopes Norberto P |
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Institution: | 1. Universidade de São Paulo, Instituto de Química, Departamento de Bioquímica, Av Professor Lineu Prestes, 748 CP 20780, CEP 05508900, São Paulo-SP, Brazil;2. Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Via do Café S/N, CEP 14040-903, Ribeirão Preto-SP, Brazil;3. Universidade de São Paulo, Faculdade de Ciências Farmacêuticas, Departamento de Análises Clínicas e Toxicológicas, Av Professor Lineu Prestes, 580 CEP 05508900, São Paulo-SP, Brazil |
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Abstract: | 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. |
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Keywords: | xanthophylls carotenoids ESI molecular ion ionization |
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