A Mass Spectrometry-Based Approach for Characterization of Red, Blue, and Purple Natural Dyes

Abstract

Effective analytical approaches for the identification of natural dyes in historical textiles are mainly based on high-performance liquid chromatography coupled with spectrophotometric detection and tandem mass spectrometric detection with electrospray ionization (HPLC-UV-Vis-ESI MS/MS). Due to the wide variety of dyes, the developed method should include an adequate number of reference color compounds, but not all of them are commercially available. Thus, the present study was focused on extending of the universal analytical HPLC-UV-Vis-ESI MS/MS approach to commercially unavailable markers of red, purple, and blue dyes. In the present study, HPLC-UV-Vis-ESI MS/MS was used to characterize the colorants in ten natural dyes (American cochineal, brazilwood, indigo, kermes, lac dye, logwood, madder, orchil, Polish cochineal, and sandalwood) and, hence, to extend the analytical method for the identification of natural dyes used in historical objects to new compounds. Dye markers were identified mostly on the basis of triple quadrupole MS/MS spectra. In consequence, the HPLC-UV-Vis-ESI MS/MS method with dynamic multiple reaction monitoring (dMRM) was extended to the next 49 commercially unavailable colorants (anthraquinones and flavonoids) in negative ion mode and to 11 (indigoids and orceins) in positive ion mode. These include protosappanin B, protosappanin E, erythrolaccin, deoxyerythrolaccin, nordamnacanthal, lucidin, santalin A, santalin B, santarubin A, and many others. Moreover, high-resolution QToF MS data led to the establishment of the complex fragmentation pathways of α-, β-, and γ- aminoorceins, hydroxyorceins, and aminoorceinimines extracted from wool dyed with Roccella tinctoria DC. The developed approach has been tested in the identification of natural dyes used in 223 red, purple, and blue fibers from 15th- to 17th-century silk textiles. These European and Near Eastern textiles have been used in vestments from the collections of twenty Krakow churches.

Mass Spectrometry for Investigation of Natural Dyes in Historical Textiles: Unveiling the Mystery behind Safflower-Dyed Fibers

“…The developed HPLC–UV–vis–ESI-MS/MS method was applied to investigate natural dyes in silk fibers accordingly to the analytical protocol proposed previously. 30 The thread samples were taken from 16th to 18th century textiles used in the vestments owned by Krakow churches. The samples, identified compounds, and dyes are presented in Table 3 .…”

“… a Bold and underlined , the main compounds; bold , the secondary compounds; nonhighlighted, the minor compounds; ct1–ct6, E/Z stereoisomers of N 1 ,N 5 ,N 10 -tri- p -coumaroylspermidine. b Identified previously and depicted in refs ( 29 and 30 ). c Detailed data presented in “ KATALOG TKANIN z zasobów kościelnych Krakowa z czasów od XV do końca XVII ” (in Polish); Krupa, N., Ed.…”

Multi-Technique Investigation of Grave Robes from 17th and 18th Century Crypts Using Combined Spectroscopic, Spectrometric Techniques, and New-Generation Sequencing

“…The identification of dyes in historical objects requires sensitive and selective analytical methods because the amount of available materials is usually limited. Among them, highperformance liquid chromatography with spectrophotometric and mass-spectrometric detectors (HPLC-UV-Vis-MS) is one of the useful tools for the analysis of textile samples containing dyes [4][5][6][7][8][9]. Tandem electrospray ionization mass spectrometry (MS/MS) can identify these compounds and enables conclusions about their structures [10][11][12][13][14].…”

Textile Dyes from Gokstad Viking Ship’s Grave

“…In the past 15 years, HPLC coupled with mass spectrometry (MS) has been successfully used for dyes analyses, providing a higher sensitivity than HPLC-DAD, which is particularly useful in the analysis of archaeological textiles, where the sample is usually small in size and contains low concentrations of time-altered colorants (see, in general, [19][20][21]). HPLC-MS also allows, thanks to the acquisition of tandem mass spectra, us to identify unknown species, thus providing information on dyes not available as reference materials [22][23][24]. Different reversed phase analytical columns have been employed for dyes analysis with mass spectrometric detection, differing in the length of the hydrophobic chains (C8 or C18), particle size (also capillary columns were employed), and end capping, or even presenting polar embedding, such as RP-amide columns [23,25].…”

“…HPLC-MS also allows, thanks to the acquisition of tandem mass spectra, us to identify unknown species, thus providing information on dyes not available as reference materials [22][23][24]. Different reversed phase analytical columns have been employed for dyes analysis with mass spectrometric detection, differing in the length of the hydrophobic chains (C8 or C18), particle size (also capillary columns were employed), and end capping, or even presenting polar embedding, such as RP-amide columns [23,25]. Recently, two-dimensional liquid chromatography was also employed successfully [26].…”