title: Rapid identification of Mg-chelated chlorins by on-line high performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry.
abstract: 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.
authors.affiliation: Laboratoire de Spectrométrie de Masse, Université de Genève, Geneva, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Verzegnassi
authors.forename: C
authors.initials: C
authors.lastname: Riffé-Chalard
authors.forename: F O
authors.initials: FO
authors.lastname: Gülaçar
mesh_terms: D001429:Bacteriochlorophylls / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D008274:Magnesium / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D011166:Porphyrins / Q000032:analysis*
chemical_list: D001429:Bacteriochlorophylls; D011166:Porphyrins; D002734:Chlorophyll; C006969:chlorin; D008274:Magnesium