Berg KJ, Boon JJ, Pastorova I, Spetter LF
MOLART Project, FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
J Mass Spectrom. 2000 Apr;35(4):512-533. doi: 10.1002/(SICI)1096-9888(200004)35:4<512::AID-JMS963>3.0.CO;2-3.
Diterpenoid resins from larch and pine trees and the corresponding fractions in a >100-year-old wax-resin adhesive and varnish and a 200-year-old resin/oil paint sample were analysed with by gas chromatography/mass spectrometry (GC/MS) using several off-line and on-line derivatization methods. The main resin compounds were highly oxidized abietic acids. Important products found are hydroxydehydroabietic acids (OH-DHAs), 7-oxoDHA, di-OH-DHAs and 15-OH-7-oxoDHA. The last two compounds have not been reported to occur in artworks before. Larixyl acetate, an important marker from larch resins, was found to be still present in high amounts in the adhesive. A large number of mass spectra of the different oxidation products and larixol and larixyl acetate are presented and their fragmentation behaviour under electron impact conditions is discussed. An index for the degree of oxidation (IDOX) of the abietic acids is presented as an indicator of the degree of oxidation of the matrix in which the resin is present. The IDOX was 0.10, 0.67, 0.81 and 0.76 for the fresh resins, the dark-aged adhesive, the aged varnish and the resin/oil paint, respectively (measured with pyrolysis (Py)-tetramethylammonium hydroxide (TMAH)-GC/MS). Py-TMAH-GC/MS and direct temperature-resolved mass spectrometry are reliable, valuable and fast techniques for the assessment of the presence and degree of oxidation of diterpenoid resins. Copyright 2000 John Wiley & Sons, Ltd.
采用多种离线和在线衍生化方法，通过气相色谱/质谱联用（GC/MS）对落叶松和松树中的二萜树脂以及在一种已有100多年历史的蜡树脂粘合剂和清漆、一个已有200年历史的树脂/油漆样品中的相应馏分进行了分析。主要的树脂化合物是高度氧化的枞酸。发现的重要产物有羟基脱氢枞酸（OH-DHAs）、7-氧代脱氢枞酸、二羟基脱氢枞酸和15-羟基-7-氧代脱氢枞酸。后两种化合物此前尚未见在艺术品中出现的报道。落叶松树脂的重要标志物乙酸落叶松酯，被发现在粘合剂中仍大量存在。给出了不同氧化产物以及落叶松醇和乙酸落叶松酯的大量质谱图，并讨论了它们在电子轰击条件下的裂解行为。提出了一种枞酸氧化程度指数（IDOX），作为树脂所在基质氧化程度的指标。新鲜树脂、老化变黑的粘合剂、老化清漆和树脂/油漆的IDOX分别为0.10、0.67、0.81和0.76（用热解（Py）-氢氧化四甲基铵（TMAH）-GC/MS测定）。Py-TMAH-GC/MS和直接温度分辨质谱法是评估二萜树脂的存在及其氧化程度的可靠、有价值且快速的技术。版权所有2000约翰威立父子有限公司。
