totalchlorine

Total chlorine refers to the sum of all chlorine-containing species present in a sample. This can include free chlorine, combined chlorine, and organically bound chlorine. Free chlorine, such as hypochlorous acid (HOCl) and hypochlorite ion (OCl-), is the active disinfecting agent in water treatment. Combined chlorine is formed when free chlorine reacts with ammonia or organic compounds, resulting in compounds like chloramines. Organically bound chlorine can exist in various forms, often resulting from the reaction of chlorine with natural organic matter.

The measurement of total chlorine is important for several reasons. In water treatment, it helps assess the overall effectiveness of chlorination and ensures that residual chlorine levels are sufficient to maintain disinfection throughout the distribution system without exceeding acceptable limits for human consumption. In environmental monitoring, total chlorine can indicate the presence of chlorinated pollutants, which can have detrimental effects on aquatic ecosystems. Analytical methods for determining total chlorine typically involve a redox reaction where chlorine species oxidize an indicator compound, producing a color change that can be measured spectrophotometrically. The specific methodology employed can influence the range of chlorine-containing species that are included in the total chlorine measurement.