title: MALDI-TOF mass spectrometry on cellulosic surfaces of fresh and photo-aged di- and triterpenoid varnish resins.
abstract: Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry (MALDI-TOF-MS) on cellulosic surfaces is shown to be a suitable method for examining highly oxidized terpenoids, which are otherwise too difficult to determine by other techniques. By crystallization of a 2,5-dihydroxybenzoic acid (DHB) matrix and the sample solution on cellulose-coated thin layer chromatography(TLC) plates, spectra with good signal/noise ratios are obtained and no significant interferences due to matrix ions or cluster ions were produced, at least not in the range of m/z values of interest (>300 Da). The validity of the method was tested on natural di- and triterpenoid resins used as paint varnishes by Old Masters. The samples were analyzed before and after artificial light ageing. Di- and triterpenoid compounds, being very sensitive towards photo-oxidation, were found as oxidized molecules even in the raw resins and in the unexposed varnish layers. Artificial ageing simulating window-filtered daylight resulted in a stronger oxidation of the original terpenoids and the incorporation of up to six oxygen atoms per molecule could be demonstrated. Terpenoid dimers and their oxidation products were also detected.
authors.affiliation: Department of IPM Chemistry, University of Torino, Via P. Giuria 7, Italy.
authors.forename: Dominique
authors.initials: D
authors.lastname: Scalarone
authors.forename: Marc C
authors.initials: MC
authors.lastname: Duursma
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: Boon
authors.forename: Oscar
authors.initials: O
authors.lastname: Chiantore
mesh_terms: D002482:Cellulose; D008401:Gas Chromatography-Mass Spectrometry; D000069997:Mastic Resin; D010084:Oxidation-Reduction; D010150:Paint / Q000032:analysis*; D010777:Photochemistry; D012116:Resins, Plant / Q000032:analysis* / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation / Q000379:methods*; D014315:Triterpenes / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification; D000097669:Dammaranes
chemical_list: D002482:Cellulose; D000069997:Mastic Resin; D012116:Resins, Plant; D014315:Triterpenes; D000097669:Dammaranes; C013893:rosin