Chlorexidine behavior in chlorinated medium and occurrence of byproducts

Chlorhexidine is the active principle of antiseptic products with antifungal and bactericidal action used in large scale for different applications (human, veterinary and general cleaning). The increasing use and disposal of these products has resulted in the contamination of several environmental compartments by chlorexidine, including waters of springs and aquifers. Data on the behavior and safety of this micropollutant, as well as their derivatives, on the environment and human health are still scarce. Regulatory agencies in Brazil and in the world have required studies that may support more specific and safe regulations. In this study chlorhexidine was investigated in chlorinated medium to verify its behavior and to detect plausible derivatives to be formed in chlorinated aquatic environments (focusing on water supply). This molecule will be subjected to conditions of pH (6-9), light (presence/absence), temperature (20 to 40°C) and chlorine concentration (0.2 to 5.0 mgL-1) usually present in the natural environment and/or applied during the treatment and distribution of water supply. Analytical methodology using liquid chromatography coupled to mass spectrometry will be developed to monitor the target molecule and identify their derivatives. Under the different conditions studied, forty-one derivatives were detected. Some of them were formed under different conditions and others formed specifically in a given condition. These compounds were formed from oxidation, fragmentation and / or chlorination of the chlorhexidine molecule generating analogues of several organic classes including chloramine, class of organic compounds with proven toxicological activity.