Quantification of Dibromodimethylhydantoin Disinfectants in Water by Chemiluminescent Method

Abstract

Quantification of 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) was studied by its chemiluminescence (CL) reaction with luminol in an alkaline medium. The stability of DBDMH, 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) and 1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH) in water was initially assessed by its CL reaction capability. The results indicated that the hydrolysis process was critically dependent on the types of reagents and their pHs. Capillary electrophoresis (CE) separation with CL detection procedure was applied to the DBDMH solution. It was found that at least 3 species in the aqueous DBDMH solution could oxidize luminol to give luminescence: one of them was confirmed to be hypobromite and the others could be the unhydrolyzed or active oxygen produced in the hydrolysis reaction. Finally, a flow-injection chemiluminescent method was proposed for the determination of DBDMH. The concentration of the analyte showed a linear relationship with the CL intensity in the range of 1.2 × 10^-10 to 1.0 × 10^-6 mol dm^-3 and the detection limit was as low as 6.2 × 10^-11 mol dm^-3. The relative standard deviation (RSD) is 1.7% (n = 9) for 2.8 × 10^-7 mol dm^-3 DBDMH.