Fluorescent assay of quinone lichen and redwood dyestuffs

Basic features of spectrofluorometry are described. Botanical sources and chemical compositions of some natural dyes used, or likely to have been used, in textile dyeings and manuscript illumination are reviewed. Their chemical compositions are liable to varying degrees of change with time, crop quality, exposure, mordanting, dyeing techniques and other procedures. Problems in evaluation of their analysis are discussed. Procedures for sample preparation and extraction are applicable to all quinone, redwood and lichen dyes. Identification of dyes is based on comparison of fluorescence emission spectra, sometimes together with excitation spectra, with those of known dyes. A description of the method is followed by some examples of analysis to illustrate possibilities and limitations. Spectrofluorometry provides a rapid, effective means for qualitative determination of dyestuffs in very small samples.