Jean-François Rontani1, Bruno Charrière2, Christophe Menniti2, Dominique Aubert2, Claude Aubert3. 1. CNRS, IRD, MIO UM 110, Aix Marseille Univ, Université de Toulon, Marseille, France, 13288, Marseille, France. 2. Centre de Formation et de Recherche sur les Environnements Méditerranéens (CEFREM, UMR CNRS UPVD 5110), 52 Avenue Paul Alduy, 66860, Perpignan Cedex, France. 3. Laboratoire de Pharmacocinétique et Toxicocinétique (EA 3286), Faculté de Pharmacie, 13385, Marseille, France.
Abstract
RATIONALE: Riverine particulate organic matter is generally considered to be refractory with respect to further decomposition in the ocean. In order to check the validity of this paradigm, there is a real need for tracers sufficiently stable and specific to monitor the degradation of terrestrial higher plant material in the environment. 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one (autoxidation products of α- and β-amyrin) were previously proposed for such use. METHODS: EIMS fragmentation pathways of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives were investigated. These pathways were deduced by: (i) low energy CID-GC/MS/MS, (ii) accurate mass measurement and (iii) deuterium labelling. Quantification of these compounds in total lipid extracts of natural samples was then carried out in MRM mode. RESULTS: CID-MS/MS analyses, accurate mass measurement and deuterium labelling experiments allowed us to elucidate EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives. Some specific fragmentation pathways, useful in addition to chromatographic retention times for further characterization, could be selected. As an application of some of the described fragmentations, TMS derivatives of these oxidation products were characterized and quantified in MRM mode in different natural samples. CONCLUSIONS: EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives exhibit specific fragment ions, which appear to be very useful for the quantification of these oxidation products in natural samples (riverine particulate matter, wet and dry deposited atmospheric particles). This article is protected by copyright. All rights reserved.
RATIONALE: Riverine particulate organic matter is generally considered to be refractory with respect to further decomposition in the ocean. In order to check the validity of this paradigm, there is a real need for tracers sufficiently stable and specific to monitor the degradation of terrestrial higher plant material in the environment. 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one (autoxidation products of α- and β-amyrin) were previously proposed for such use. METHODS: EIMS fragmentation pathways of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives were investigated. These pathways were deduced by: (i) low energy CID-GC/MS/MS, (ii) accurate mass measurement and (iii) deuterium labelling. Quantification of these compounds in total lipid extracts of natural samples was then carried out in MRM mode. RESULTS:CID-MS/MS analyses, accurate mass measurement and deuterium labelling experiments allowed us to elucidate EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives. Some specific fragmentation pathways, useful in addition to chromatographic retention times for further characterization, could be selected. As an application of some of the described fragmentations, TMS derivatives of these oxidation products were characterized and quantified in MRM mode in different natural samples. CONCLUSIONS: EIMS fragmentations of 3β-hydroxy-urs-12-en-11-one and 3β-hydroxy-olean-12-en-11-one TMS derivatives exhibit specific fragment ions, which appear to be very useful for the quantification of these oxidation products in natural samples (riverine particulate matter, wet and dry deposited atmospheric particles). This article is protected by copyright. All rights reserved.