Photochemical reaction of trihalomethanes with diphenylamine in organic media and its analytical application

Photochemical reaction of trihalomethanes (THMs) such as dichlorobromomethane (CHBrCl2), dibromochloromethane (CHBr2Cl), and bromoform (CHBr3) with diphenylamine (DPA) in acetonitrile (CH3CN) leading to a fluorescent product (lambda (cm): 480 nm, lambda (ex): 400 nm) has been studied for the first time. The fluorescence intensity of the product is a direct measure of THM concentration. The limits of detection (LODs) are in the sub parts per million (ppm) levels and can further be lowered through pre-extraction step. The photochemical reaction of CHBr3 with DPA for its quantification through fluorescence analysis has been utilized. The effect of reagent concentration, irradiation time, solvent and interfering substances are discussed. The statistical parameters are reported. The method can be applied for CHBr3 detection in water samples also.