Analysis of natural red dyes (cochineal) in textiles of historical importance using HPLC and multivariate data analysis

Abstract

A new analytical approach based on high-performance liquid chromatography with diode array detector (HPLC-DAD) and multivariate data analysis was applied and assessed for analyzing the red dye extracted from cochineal insects, used in precious historical textiles. The most widely used method of analysis involves quantification of specific minor compounds (markers), using HPLC-DAD. However, variation in the cochineal markers concentration, use of aggressive dye extraction methods and poor resolution of HPLC chromatograms can compromise the identification of the precise insect species used in the textiles. In this study, a soft extraction method combined with a new dye recovery treatment was developed, capable of yielding HPLC chromatograms with good resolution, for the first time, for historical cochineal-dyed textiles. After principal components analysis (PCA) and mass spectrometry (MS), it was possible to identify the cochineal species used in these textiles, in contrast to the accepted method of analysis. In order to compare both methodologies, 7 cochineal species and 63 historical cochineal insect specimens were analyzed using the two approaches, and then compared with the results for 15 historical textiles in order to assess their applicability to real complex samples. The methodology developed here was shown to provide more accurate and consistent information than the traditional method. Almost all of the historical textiles were dyed with Porphyrophora sp. insects. These results emphasize the importance of adopting the proposed methodology for future research on cochineal (and related red dyes). Mild extraction methods and HPLC-DAD/MS(n) analysis yield distinctive profiles, which, in combination with a PCA reference database, are a powerful tool for identifying red insect dyes.

Analysis of natural dyes and metal threads used in 16th -18th century Persian/Safavid and Indian/Mughal velvets by HPLC-PDA and SEM-EDS to investigate the system to differentiate velvets of these two cultures

“…Natural dyes whose major colorant is carminic acid are known to be American cochineal (Dactylopius coccus Costa), Polish cochineal (Porphyrophora polonica Linnaeus), and Armenian cochineal (Porphyrophora hamelii Brandt) and possibly cochineals of other species of Dactylopius and Porphyrophora genus. The composition of colorants in those cochineals is similar [25][26][27]. Therefore, those red piles appeared to be dyed with one of those cochineals.…”

“…The structure of the dcII was identified as 7-C-glycoside of flavokermesic acid [28]. Further, Serrano et al [27] developed the system using multivariate data analysis to differentiate those different species of cochineals. In this paper, the system had not yet been applied to differentiate them, and the species of cochineals used on those red thread samples was not determined.…”

FTIR imaging and HPLC reveal ancient painting and dyeing techniques of molluskan purple

“…Chromatography can easily provide quantitative results for the compounds detected in an archaeological sample. This can be extremely important to identify the exact biological source of a dye, as it was shown, for instance, for cochineal (Serrano et al 2011;Wouters and Verhecken 1989), madder (Wouters 2001), dragon's blood (Sousa et al 2008) and Tyrian purple (Karapanagiotis et al 2013;Koren 2008) species. Mass spectrometric techniques are also very useful for dye characterisation and can provide important information about the structures of the dye molecules (Mantzouris et al 2011;Michel et al 1992aMichel et al , 1992b.…”

Kinetic Study of the Equilibration between Carminic Acid and Its Two Isomers Isolated from Cochineal Dye

“…Historically, this dye was used predominantly for coloring artwork and textiles, 1) but currently it is also used worldwide in food additives, cosmetics and pharmaceuticals. Cochineal dye is a generally highly safe material, but occasionally induces harmful allergic reactions including anaphylaxis, urticarial and occupational asthma.…”

“…In addition, the minor components in food additives, colored textiles and historical artwork generally have been required to identify the species and the geographical origin of the cochineal by using multivariate statistical methods such as principal components analysis, partial-least squares discriminant analysis and hierarchical cluster analysis. 1,[6][7][8][9][10] The quality, insect species, and geographical origin of cochineal dye are typically evaluated using an HPLC equipped with a UV-Vis detector 6,7,11,12) and a photodiode array detector 1,[13][14][15] to determine carminic acid (CA), the main constituent of cochineal, as well as minor components.…”