Universal analytical method for characterization of yellow and related natural dyes in liturgical vestments from Krakow

Due to the diversity of dyes, as well as the multiplicity of colorants occurring in them, their identification in historical objects requires the development of an effective analytical approach including also the separation step. Thus, the present study was focused on high-performance liquid chromatography (with a reversed phase phenyl column) coupled with spectrophotometric and tandem mass spectrometric detections with electrospray ionization (HPLC–UV–Vis–ESI MS/MS) to develop a universal analytical approach dedicated to a comprehensive analysis of wide range of dyes. Optimization of ion source parameters led to a total increment in intensity of peaks even up to 64%. The final method, developed using dynamic multiple reaction monitoring mode (dMRM), includes 112 colorants in negative ion mode and/or 12 in positive ion mode, 62 of which are reference compounds, while 54 are compounds identified by tandem mass spectrometry in fibers dyed with 10 examined yellow and orange dyes (annatto, cutch, dyer's broom, old fustic, Osage orange, saffron, sawwort, Persian berries, weld and young fustic). The developed method was tested for the identification of natural dyes in yellow, orange, brown and green fibers from 15th- to 17th-century textiles used in the vestments from the collections of seventeen Krakow churches. In this way, annatto and sawwort have been found in historical samples using HPLC–UV–Vis or HPLC–ESI MS/MS for the first time.