title: Atmospheric pressure chemical ionisation normal phase liquid chromatography mass spectrometry and tandem mass spectrometry of chlorophyll a allomers.
abstract: Four oxidation products formed during the allomerisation reaction of chlorophyll a in methanol have been separated and identified using normal phase high-performance liquid chromatography (NP-HPLC) coupled with atmospheric pressure chemical ionisation (APCI) tandem mass spectrometry (MS/MS) and photodiode array detection. Fragmentation pathways of the main stereoisomers of the four major products, Mg-purpurin-7 dimethyl phytyl ester, 15(1)-MeO-lact-chl a, 13(2)-MeO-chl a and 13(2)-HO-chl a, have been assigned using APCI-MS(n) aided by examination of deuteriated counterparts of the purpurin and the lactone. Diagnostic fragmentations have been determined, including those for Mg-purpurin-7 dimethyl phytyl ester and 15(1)-MeO-lact-chl a, which display very similar full MS and MS/MS spectra. The use of NP-HPLC offers a rapid and efficient method which, combined with MS/MS, reduces reliance on precursor ion mass for assignment of structure in the allomerisation reaction where major and minor components are often isobaric.
authors.affiliation: Department of Chemistry, University of York, Heslington, York Y010 5DD, UK.
authors.forename: Chi
authors.initials: C
authors.lastname: Jie
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Walker
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Keely
mesh_terms: D002734:Chlorophyll / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D007202:Indicators and Reagents; D007536:Isomerism; D013058:Mass Spectrometry; D000432:Methanol; D012997:Solvents; D018724:Spinacia oleracea / Q000737:chemistry*
chemical_list: D007202:Indicators and Reagents; D012997:Solvents; D002734:Chlorophyll; D000432:Methanol