Diazotization employing coupling reactions is the
most generally used method of assay for sulfonamide
drugs containing a free aromatic amino group or yielding
an aromatic amino group upon hydrolysis or reduction.
To the best of our knowledge, this selective reaction
was not extended for the determination of FUR.
Though FUR does not contain a free primary aromatic
amino group its formation in the subsequent diazotization
and coupling reactions is proposed (Fig. 1). The
proposed reaction steps are similar to the diazotization
procedure of succinyl-sulfathiazole and phthalylsulfathiazole
(Higuchi & Brochmann-Hassan, 1997) after
the generation of a free amino group upon hydrolysis
of the acyl group.