5-amino-4-sulfanylphthalhydrazide as a chemiluminescence derivatization reagent for aromatic aldehydes in liquid chromatography

5-Amino-4-sulfanylphthalhydrazide (ASPH) was synthesized as a chemiluminesc ence derivatization reagent for aromatic aldehydes in liquid chromatography (LC). Benzaldehyde, 4-tolualdehyde, 4-chlorobenzaldehyde, 4-formylbenzoic acid, 4-hydroxybenzaldehyde and vanillin were used as model compounds to op timize the derivatization conditions. This reagent, ASPH, reacts selectivel y with aromatic aldehydes in the presence of sodium sulfite and disodium hy drogenphoshite in acidic medium at 100 degreesC to give the corresponding h ighly chemiluminescent 2-arylbenzothiazole derivatives. The resulting deriv atives generated intense chemiluminescence by reaction with hydrogen peroxi de and potassium hexacyanoferrate(ml in alkaline solution. The ASPH derivat ives of aromatic aldehydes were separated by reversed-phase liquid chromato graphy with isocratic elution, and detected chemiluminometrically after mix ing with oxidizing agents. The detection limits (signal-ro-noise ratio=3) f or aromatic aldehydes are in the range 0.2-4.0 fmol for a 20-mul injection volume. Currently, the method is not effective for aliphatic aldehydes beca use of interfering LC peaks. (C) 2000 Elsevier Science BN. All rights reser ved.