Germinario Giulia, Garrappa Silvia, D'Ambrosio Valeria, van der Werf Inez Dorothé, Sabbatini Luigia
Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70125, Bari, Italy.
Centro interdipartimentale "Laboratorio di ricerca per la diagnostica dei Beni Culturali", Università degli Studi di Bari Aldo Moro, via Orabona 4, 70125, Bari, Italy.
Anal Bioanal Chem. 2018 Jan;410(3):1079-1094. doi: 10.1007/s00216-017-0687-x. Epub 2017 Nov 2.
Felt-tip pens are frequently used for the realization of sketches, drawings, architectural projects, and other technical designs. The formulations of these inks are usually rather complex and may be associated to those of modern paint materials where, next to the binding medium and pigments/dyes, solvents, fillers, emulsifiers, antioxidants, plasticizers, light stabilizers, biocides, and so on are commonly added. Felt-tip pen inks are extremely sensitive to degradation and especially exposure to light may cause chromatic changes and fading. In this study, we report on the complete chemical characterization of modern felt-tip pen inks that are commercially available and commonly used for the realization of artworks. Three brands of felt-tip pens (Faber-Castell, Edding, and Stabilo) were investigated with complementary analytical techniques such as thin-layer chromatography (TLC), VIS-reflectance spectroscopy, μ-Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), GC-MS, and Fourier transform infrared (FTIR) spectroscopy. The use of TLC proved to be very powerful in the study of complex mixtures of synthetic dyes. First derivatives of the reflectance spectra acquired on the TLC spots were useful in the preliminary identification of the dye, followed by Raman spectroscopy and SERS, which allowed for the unambiguous determination of the chemical composition of the pigments (phthalocyanines, dioxazines, and azo pigments) and dyes (azo dyes, triarylmethanes, xanthenes). FTIR spectroscopy was used especially for the detection of additives, as well as for confirming the nature of solvents and dyes/pigments. Finally, (Py-)GC-MS data provided information on the binders (styrene-acrylic resins, plant gums), solvents, and additives, as well as on pigments and dyes.
毡尖笔常用于绘制草图、图纸、建筑项目和其他技术设计。这些墨水的配方通常相当复杂，可能与现代涂料材料的配方相关，除了粘结介质和颜料/染料外，通常还会添加溶剂、填料、乳化剂、抗氧化剂、增塑剂、光稳定剂、杀生剂等。毡尖笔墨水极易降解，尤其是暴露在光线下可能会导致颜色变化和褪色。在本研究中，我们报告了市售且常用于艺术品创作的现代毡尖笔墨水的完整化学特征。使用薄层色谱法（TLC）、可见反射光谱法、显微拉曼光谱法、表面增强拉曼光谱法（SERS）、热解气相色谱-质谱联用仪（Py-GC-MS）、气相色谱-质谱联用仪（GC-MS）和傅里叶变换红外光谱法（FTIR）等互补分析技术，对三个品牌的毡尖笔（辉柏嘉、艾迪、施德楼）进行了研究。事实证明，TLC在研究合成染料的复杂混合物方面非常有效。在TLC斑点上采集的反射光谱的一阶导数有助于染料的初步鉴定，随后通过拉曼光谱和SERS可以明确确定颜料（酞菁、二恶嗪和偶氮颜料）和染料（偶氮染料、三芳基甲烷、呫吨）的化学成分。FTIR光谱尤其用于检测添加剂，以及确认溶剂和染料/颜料的性质。最后，（Py-）GC-MS数据提供了有关粘合剂（苯乙烯-丙烯酸树脂、植物胶）、溶剂、添加剂以及颜料和染料的信息。
