42nd Annual Meeting, Textiles Session, May 29th: Analysis of Organic Dyes in Textiles by Direct Analysis in Real Time–Time-of-Flight Mass Spectrometry by Cathy Selvius-DeRoo, Ruth Ann Armitage

Direct Analysis in Real Time – Time of Flight Mass Spectrometry (DART-TOF) was shown to be a viable method of organic dye analysis in the presentation by Cathy Selvius-DeRoo. The beauty of the technique is that it requires only a small fiber sample, and no advanced preparation such as dye extraction, in order to get positive identification for a variety of dyes, both plant and insect based.
The project began with a grant to purchase the equipment.  From there, various colorants were tested from a dye sample book, in order to develop the protocol.  The sample was put in the ionizing gas airstream (helium) and heated to a temperature of 350 – 500 degrees.  The result was fast and accurate identification of several dye classes, such as quinones, tannins and indigoids.
The presenter had a relaxed, personable style and shared some of her tips for success as well as lessons learned, including: better results were achieved with the higher temperature and with the addition of acid hydrolysis, which could be added just prior to putting the sample in the airstream using an eyedropper. The presenter confessed that flavonoids could be difficult to discern because the spectra are very similar for the various components.
After the method proved reliable, the technique was tested on textiles with undocumented dyes.  The most satisfying was to substantiate family lore on a Civil War coat.  The story was that a mother of a soldier dyed a Union issued coat to resemble a Confederate coat.  Analysis revealed that the indigo was overdyed with Walnut (also referred to as Butternut). Cool.
Full disclosure – I signed up for blogging this talk because I’m a bit of a science junkie.  I don’t always understand it, and in a small private practice, I certainly don’t have a Mass Spectrometer in the studio, but I appreciate knowing how to solve problems and who to go to for help.