Development of a novel chemiluminescent probe, 4-(5ʹ,6ʹ-Dimethoxybenzothiazolyl) phthalhydrazide

4-(5ʹ,6ʹ-Dimethoxybenzothiazolyl)phthalhydrazide (DBPH) was synthesized as a new, highly sensitive chemiluminescent reagent. The reagent consists of phthalhydrazide and benzothiazole moieties and generates strong chemiluminescence by reaction with hydrogen peroxide in the presence of potassium hexacyanoferrate(III) or peroxidase. The chemiluminescence intensity of DBPH was about 20 times greater than that of luminol. The detection limit of DBPH was 1.3 × 10−11 M [0.65 fmol per well (200 μl), signal to blank ratio = 2]. The reaction of DBPH was also applied to the determination of hydrogen peroxide by flow injection. The detection limit is 0.5 pmol for a 100-μl injection.