sigma Aldrich offers xylene cyanol.

Product number:

X4126 Sigma

Also if you specify which protocol and maybe post it, it might be possible to find out what it is used for.

I think almost every biochemical supplier (Sigma, Thermo, Santa cruz, MPbio etc.) provide Xylene Cyanole F.F. For example: ( http://www.sigmaaldrich.com/catalog/product/sigma/x4126?lang=de®ion=DE)

I think its used as a tracker in gel filtration to get rid of unconjugated FITC (migrates together with the free FITC).

Hope it helps: Manoj

Answers to these questions can be found with the help of reversible methods or reverse engineering. So we do not need to use Empire. First we need to understand the essence of reality given, and only then perform empirical research.