Van 't Hoff Institute for Molecular Sciences, Faculty of Science, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, Netherlands.
Centre of Analytical Sciences Amsterdam, Science Park, 904, 1098 XH Amsterdam, The Netherlands.
J Am Soc Mass Spectrom. 2021 Feb 3;32(2):444-454. doi: 10.1021/jasms.0c00272. Epub 2020 Dec 9.
The sensitive surfaces of many unvarnished 20th century oil paintings are of great concern for conservators and collection keepers. They may show degradation problems such as paint delamination, dripping, and soft and sticky paint and pose challenges for cleaning due to solvent sensitivity. We report for the first time the use of an innovative ambient ionization technique, surface acoustic wave nebulization-mass spectrometry (SAWN-MS), for the identification and characterization of fatty acids, dicarboxylic species and glycerides in water-sensitive modern oil paints. The composition of 10 relevant Winsor and Newton 1964-1965 paint swatches that present different degrees of water sensitivity and two paint samples from a painting by the British artist Francis Bacon were studied. Principal component analysis was used for SAWN-MS data classification. Electrospray ionization (ESI)-MS was used as control method, specifically to compare the obtained ratios of markers of interest by the two ionization techniques. The results obtained by both ESI-MS and SAWN-MS are correlated and discussed in a broader context including the information on the oil media obtained by gas chromatography (GC-MS) and also on the inorganic materials and salts characterized using a combination of methods in previous reports on samples from the same manufacturer. SAWN-MS was found to be a suitable tool for the determination of soluble organic constituents present in the paints. The method provides an indication of the level of oxidation and hydrolysis of the paint film by monitoring specific markers such as free palmitic and stearic acids, azelaic acid, monoacylglycerols, and diacylglycerols. The data showed that a higher level of water sensitivity coupled with a high level of oxidation and hydrolysis is linked to higher dicarboxylic acid, diacyl- and triacylglyceride content and lower levels of short chain fatty acids. The data obtained by SAWN-MS provided a good correlation between the monitored species and the degree of water sensitivity.
许多未经上光处理的 20 世纪油画的敏感表面令文物保护者和收藏者十分关注。它们可能会出现漆膜分层、滴流以及漆膜变软发黏等降解问题，而且由于溶剂敏感性，清洁工作也颇具挑战。我们首次报道了一种创新的环境电离技术，即表面声波雾化质谱法（SAWN-MS），用于鉴定和表征水溶性现代油画中的脂肪酸、二羧酸物质和甘油酯。研究了 10 个相关的温莎牛顿 1964-1965 年油漆样本的组成，这些样本具有不同程度的水溶性，以及英国艺术家弗朗西斯·培根一幅画中的两个油漆样本。采用主成分分析对 SAWN-MS 数据进行分类。采用电喷雾电离（ESI）-MS 作为对照方法，特别是比较两种电离技术获得的感兴趣标志物的比值。通过 ESI-MS 和 SAWN-MS 获得的结果进行了相关性讨论，并置于更广泛的背景下进行讨论，包括通过气相色谱（GC-MS）获得的油介质信息，以及通过之前关于同一制造商样本的报告中结合使用的方法获得的无机材料和盐的信息。结果表明，SAWN-MS 是一种用于确定油漆中存在的可溶有机成分的合适工具。该方法通过监测特定标志物（如游离棕榈酸和硬脂酸、壬二酸、单酰基甘油和二酰基甘油），提供了漆膜氧化和水解程度的指示。数据表明，更高的水溶性水平加上更高的氧化和水解水平与更高的二羧酸、二酰基和三酰基甘油含量以及更低的短链脂肪酸水平相关。SAWN-MS 获得的数据在监测物种与水溶性之间提供了良好的相关性。
