The molecular characterization of early synthetic dyes in E. Knecht et al's textile sample book “A Manual of Dyeing” (1893) by high performance liquid chromatography - Diode array detector - Mass spectrometry (HPLC-DAD-MS)

Abstract

This study focuses on the analysis of 61 samples taken from wool fabric specimens present in the appendix of the book “A Manual of Dyeing: For the Use of Practical Dyers, Manufacturers, Students, and All Interested in the Art of Dyeing” by E. Knecht, C. Rawson and R. Loewenthal, published in England in 1893. This manual is a valuable source of information, as it partially describes the chemistry of the molecules used to dye the specimens. The dyes are presented with the common commercial names used at the end of the 19th century and the publication date ensures that they were all synthesized before 1893.The first aim of the study was to explore the correspondence between the dyes described in the manual and the molecules actually present in the samples. High performance liquid chromatography coupled to diode array and mass spectrometric detectors (HPLC-DAD-MS) was used for the molecular characterization of the samples. The results were integrated with a thorough search of historic information on early synthetic dyes, to clarify the dye nomenclature, and ultimately the molecular structures of the detected molecules.The results showed that the labels reported in the manual often do not correspond to the actual dyes present in the samples. In a number of cases, mixtures of dyes of different categories were actually used to obtain a certain color shade. We created a database of more than 160 molecules, including their UV–Vis absorption spectra and MS details, many of which are not reported in the scientific literature. This represents a valuable new comparative dataset useful for the identification of these molecules in historic samples.