FIBER-SAFE EXTRACTION OF RED MORDANT DYES FROM HAIR FIBERS
ERICA J. TIEDEMANN, & YIQI YANG
It has been shown that madder, Relbunium and cochineal on an alum mordant can be extracted by a solution of 0.1% EDTA in water/DMF (1/1 v/v). Although the extracted fibers retain some color, the EDTA/DMF extraction method can be as powerful as the conventional strong acid extraction. Consequently, fiber specimens need not be larger than 2 mg for spectral detection. Like the strong acid extracts, the EDTA/DMF extracts give a specific absorbance curve for each dye. Thus the new extraction method is compatible with UV/VIS spectrophotometry, an established dye identification method.
Unlike the strong acid extraction, the EDTA/DMF extraction is effective without destroying protein fibers. Because the dye is safely extracted without dissolving the substrate, the fibers remain useful for other research.
The usefulness of this method has not yet been tested for TLC or HPLC analysis. Perhaps chromatographic separation of the fiber extracts will reveal which dyes remain on the fiber after extraction. It is assumed that there will be little or no amino acid noise in HPLC because the fiber does not break down during extraction.
We gratefully acknowledge the assistance of Max Saltzman, who generously provided samples of Relbunium-dyed yarn for this study. We appreciate the cooperation of Maarten van de Guchte and the Krannert Art Museum. Also, we would like to thank Shiqi Li for his assistance in the laboratory. This research was funded by the University of Illinois Agricultural Experiment Station (Hatch 60-370 SHRFS).