I need to increase sensitivity for substituted anilines, greater than I can obtain by HPLC-UV detector because of matrix interferences at low levels (so far I can quantitate down to about 10 ppm in this matrix). I am interested in post-column reaction with fluorescence reagents, as I already have a fluorescence detector and could retain my current column and water/acetonitrile mobile phase. Anybody know of a working procedure with recipe and conditions for this?

Aniline and methyl substituted anilines have native fluorescence but only in their undissociated forms. It is the free electrons in the amino group which is capable of donating electrons to the aromatic ring and increase fluorescence. Once the amino goup becomes positive due to lower pH, the fluorescence is quenched. I would try mobile phase pH's as high as the column will withstand to optimize the native fluorescence of methyl substituted anilines. If a derivative is preferred then you could try a fluorophore which attacks a primary amine group such as orthopthalaldehyde (OPA) or naphalene dicarboxyaldehye (NDA). There are potentially others such as fluorescamine and dansyl chloride.