Department of Conservation of Antiquities and Works of Art, University of West Attica, 12243 Egaleo, Greece.
Molecules. 2021 Oct 3;26(19):6005. doi: 10.3390/molecules26196005.
In a cultural heritage context, fatty acids are usually found as breakdown products of lipid-containing organic remains in archaeological findings, binders in aged oil paintings, and additives in modern art-related materials. They may further interact with the ionic environment transforming into metal soaps, a process that has been recognized as a threat in aged paintings but has received less attention in archaeological objects. The investigation of the above related categories of materials with infrared spectroscopy can provide an overall picture of the organic components' identity and demonstrate their condition and prehistory. The capability of investigating and distinguishing fatty acids and their metal soaps through their rich infrared features, such as the acidic carbonyl, the carboxylate shifts, the variable splits of alkyl chain stretching, bending, twisting, wagging, and rocking vibrations, as well as the hydroxyl peak envelopes and acid dimer bands, allows for their direct detailed characterization. This paper reviews the infrared spectra of selected saturated fatty monoacids and diacids, and their corresponding sodium, calcium, and zinc salts and, supported by newly recorded data, highlights the significance of their spectroscopic features.
在文化遗产背景下,脂肪酸通常作为考古发现中含脂有机残留物的分解产物、老化油画中的粘合剂以及现代艺术相关材料中的添加剂而存在。它们可能进一步与离子环境相互作用,转化为金属皂,这一过程在古老的画作中已被认为是一种威胁,但在考古文物中受到的关注较少。用红外光谱法对上述相关类别的材料进行研究,可以全面了解有机成分的身份,并展示其状况和史前史。通过其丰富的红外特征,如酸性羰基、羧酸盐位移、烷基链伸缩、弯曲、扭曲、摆动和摇摆振动以及羟基峰包络和酸二聚体带的可变分裂,调查和区分脂肪酸及其金属皂的能力,使它们能够直接进行详细的特征描述。本文综述了选定的饱和脂肪酸单酸和二酸及其相应的钠盐、钙盐和锌盐的红外光谱,并结合新记录的数据,突出了它们光谱特征的重要性。