Chemiluminescence investigation of carbon dioxide-enhanced oxidation of dihydralazine sulfate by peroxynitrite and its application to pharmaceutical analysis

A weak chemiluminescence (CL) emission was observed upon mixing peroxynitrite (ONOO−) with dihydralazine sulfate (DHZS). Further experiments showed that carbonate media could enhance the CL emission significantly. Based on these observations, a novel flow injection CL method for the determination of DHZS is developed. The CL signal is linearly with DHZS concentration in the range of 0.01–3.0 μg mL−1 with a detection limit of 3.6 ng mL−1. The method was applied to the analysis of DHZS in pharmaceutical preparations and compared well with the high-performance liquid chromatography (HPLC) method. The CL mechanism is discussed and it is postulated that it involves nitrosoperoxocarboxylate (ONOOCO2−), which is an unstable adduct and can rapidly decompose into NO2 and CO3− radical. The latter can then oxidize DHZS to give out strong CL emission.