Sector Research Movable Heritage, Cultural Heritage Agency of the Netherlands (RCE), P.O. Box 1600, 3800 BP, Amersfoort, The Netherlands; CHAM (Portuguese Centre for Global History), Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa e Universidade dos Açores, Avenida de Berna, 1069-061 Lisboa, Portugal.
Sector Research Movable Heritage, Cultural Heritage Agency of the Netherlands (RCE), P.O. Box 1600, 3800 BP, Amersfoort, The Netherlands; Analytical Chemistry, IMM, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Anal Chim Acta. 2015 Oct 15;897:116-27. doi: 10.1016/j.aca.2015.09.046. Epub 2015 Oct 3.
The colorant behaviour of cochineal and kermes insect dyes in 141 experimentally-dyed and 28 artificially-aged samples of silk and wool was investigated using ultra-high performance liquid chromatography coupled to photodiode array detector (UHPLC-PDA), liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS) and image scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDX). Partial-least squares discriminant analysis (PLS-DA) was then used to model the acquired UHPLC-PDA data and assess the possibility of discriminating cochineal insect species, as well as their correspondent dyed and aged reference fibres. The resulting models helped to characterize a set of 117 red samples from 95 historical textiles, in which UHPLC-PDA analyses have reported the presence of cochineal and kermes insect dyes. Analytical investigation of the experimentally-dyed and artificially-aged fibres has demonstrated that the ratio of compounds in the insects dye composition can change, depending on the dyeing conditions applied and the type of fibres used. Similarities were observed when comparing the UHPLC-MS and SEM-EDX results from the dyed and aged references with the historical samples. This was verified with PLS-DA models of the chromatographic data, facilitating the classification of the cochineal species present in the historical samples. The majority of these samples were identified to contain American cochineal, which is in agreement with historical and dye identification literature that describe the impact of this dyestuff into European and Asian dyeing practices, after the Iberian Expansion in the 16th century. The analytical results emphasize the importance of using statistical data interpretation for the discrimination of cochineal dyes, besides qualitative and quantitative evaluation of chromatograms. Hence, the combination of UHPLC-PDA with a statistical classification method, such as PLS-DA, has been demonstrated to be an advisable approach in future investigations to assess closely related species of natural dyes in historical textile samples. This is particularly important when aiming to achieve more accurate interpretations about the history of works of art, or the application of natural dyes in old textile production.
采用超高效液相色谱-光电二极管阵列检测联用(UHPLC-PDA)、液相色谱-电喷雾电离质谱联用(LC-ESI-MS)和扫描电子显微镜-能量色散 X 射线光谱联用(SEM-EDX)，对 141 份经实验染色和 28 份人工老化的丝绸和羊毛样本中的胭脂红和角倍胭脂虫染料的颜色行为进行了研究。然后，采用偏最小二乘判别分析(PLS-DA)对获得的 UHPLC-PDA 数据进行建模，以评估区分胭脂红昆虫种类及其相应染色和老化参考纤维的可能性。所得模型有助于对 95 件历史纺织品中的 117 件红色样本进行特征描述，其中 UHPLC-PDA 分析报告中存在胭脂红和角倍胭脂虫染料。对实验染色和人工老化纤维的分析研究表明，昆虫染料组成中化合物的比例可能会发生变化，这取决于所应用的染色条件和所使用的纤维类型。比较染色和老化参考纤维的 UHPLC-MS 和 SEM-EDX 结果时观察到了相似性。这通过对色谱数据的 PLS-DA 模型进行了验证，有助于对历史样本中存在的胭脂红种类进行分类。这些样本中的大多数被鉴定为含有美洲胭脂红，这与描述这种染料对 16 世纪伊比利亚扩张后欧洲和亚洲染色实践影响的历史和染料鉴定文献是一致的。分析结果强调了在胭脂红染料的鉴别中使用统计数据分析的重要性，除了对色谱图进行定性和定量评估之外。因此，UHPLC-PDA 与统计分类方法（如 PLS-DA）相结合，已被证明是未来评估历史纺织品样本中天然染料近缘种的一种明智方法。当旨在更准确地解释艺术品的历史或旧的纺织品生产中天然染料的应用时，这一点尤为重要。
