6-Isothiocyanatobenzo [g] phthalazine-1,4 (2H,3H)-dione as a highly sensitive chemiluminescence derivatization reagent for amines in liquid chromatography

6-Isothiocyanatobenzo [g] phthalazine-1,4 (2H,3H)-dione was synthesized as a highly sensitive and selective chemiluminescence derivatization reagent for primary and secondary amines in liquid chromatography. Di-n-butylamine, dibenzylamine and n-nonylamine were used as model compounds to optimize the derivatization conditions. The reagent reacts selectively with amines in the presence of triethylamine to give highly chemiluminescent derivatives which produce chemiluminescence by reaction with hydrogen peroxide in the presence of potassium hexacyanoferrate (III) in alkaline solution. The chemiluminescent derivatives of the three amines can be separated within 12 min by reversed-phase liquid chromatography with isocratic elution, followed by chemiluminescence detection. The detection limits (signal-to-noise ratio= 3) for primary and secondary amines are in the range 30–120 and 0.8–3 fmol for a 20-μl injection, respectively.