Rapid identification of Mg-chelated chlorins by on-line high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry

• Published in: Rapid communications in mass spectrometry 2000-01, Vol.14 (7), p.590-594
• Main Authors: Verzegnassi, Ludovica, Riffé-Chalard, Catherine, Gülaçar, Fazil O.
• Format: Article
• Language: English
• Subjects: Bacteriochlorophylls - analysis; Chlorophyll - analysis; Chromatography, High Pressure Liquid; Magnesium - analysis; Mass Spectrometry - methods; Molecular Structure; Porphyrins - analysis
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/(SICI)1097-0231(20000415)14:7<590::AID-RCM917>3.0.CO;2-P

On‐line high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI‐MS) has been applied to the identification of a number of tetrapyrrolic pigments as well as several magnesium‐free analogs. Mass spectra, acquired both in positive (+) and negative (−) ionization mode, allow not only the determination of the structural features of the pigments, but also a very easy differentiation of the Mg‐chelated pigments from the free bases. In the positive ionization mode, all pigments show mainly a [M + H]+ ion and a [M + H − C20H38]+ fragment ion corresponding to the loss of the phytyl chain via a hydrogen rearrangement. In the negative ionization mode, on the other hand, although all pigments give an abundant molecular anion [M]−·, only the Mg‐chelated chlorin spectra show a prominent fragment [M − C20H39]− produced by a formal loss of the phytyl radical. Copyright © 2000 John Wiley & Sons, Ltd.