Faculty of Chemistry, Jagiellonian University, Cracow, Poland.
Anal Bioanal Chem. 2011 Mar;399(9):3271-83. doi: 10.1007/s00216-010-4460-7. Epub 2010 Dec 17.
An important issue connected with conservation chemistry is how to improve the storage and exposure conditions in order to suppress the fading and degradation of dyes and other components of paintings. Although the oxygen-free exposure cassettes are commonly known in museums, there is still lack of information in the literature about the effect of anoxic conditions on the degradation of dyes. This study is an attempt to start a database formation on the dyes degradation. Five commercial dyes (indigo, dragon's blood, curcumin, madder, carminic acid) were submitted to accelerated ageing by exposure to intensive light in the visible range in both oxygen-free (anoxia) and -rich conditions. Degradation of the samples was investigated by several analytical techniques (attenuated total reflectance infrared spectroscopy, Raman spectroscopy, reflectance UV-Vis spectroscopy, X-ray fluorescence spectroscopy and optical microscopy). The conclusions are based on the estimators (derived from the determination of colour differences from Vis spectra and from the changes in FTIR and Raman vibrational bands intensity). According to them, only indigo, dragon's blood and curcumin show greater stability in anoxic conditions in comparison with oxygen-rich ones while madder, carminic acid undergo greater degradation.
与保存化学有关的一个重要问题是如何改善储存和暴露条件，以抑制染料和绘画其他成分的褪色和降解。尽管在博物馆中通常都知道无氧暴露盒，但关于缺氧条件对染料降解的影响，文献中仍然缺乏信息。本研究试图开始建立一个关于染料降解的数据库。将五种商业染料（靛蓝、龙血竭、姜黄素、茜草和胭脂红酸）暴露在富氧和无氧条件下，用可见光进行强化光照，以加速其老化。通过几种分析技术（衰减全反射红外光谱、拉曼光谱、反射紫外可见光谱、X 射线荧光光谱和光学显微镜）研究了样品的降解。结论是基于从可见光谱测定色差和从 FTIR 和拉曼振动带强度变化中得出的估计值。根据这些估计值，只有靛蓝、龙血竭和姜黄素在无氧条件下比富氧条件下更稳定，而茜草和胭脂红酸则经历了更大的降解。
