Dyes: Remazol Red F-3B (C.I. Reactive Red
180) (Fig. 1(a)) was provided by DyStar and Pro-
cion Red MX-5B (C.I. Reactive Red 2) (Fig. 1(b))
was provided by BASF. The structures of both dyes are shown below in their azo tautomeric
form. Although these commercial samples contain
inorganic salts and organic formulating agents the
dyes have been used without further puri®cation.