Fundamental studies of the reaction between nicotinamide and drinking water disinfection by -products with the application to on-line monitoring

Halogenated organic disinfection by-products (DBPs) are formed as a result of excessive chlorination. The two most commonly monitored classes of DBPs are the trihalomethanes (THMs) and the haloacetic acids (HAAs). Most analytical methods for measuring these species are designed for routine drinking water sampling where samples are taken on monthly or quarterly schedules. However, when higher sampling rates are needed these methods may become quite cumbersome. Moreover, these methods are typically carried out with bench-top sized analyzers, and automation can be quite difficult and expensive. There is interest among researchers in the development of analytical methods to monitor THM and HAA concentrations in real-time or near real-time.;The primary objective of this research was to develop a capillary membrane sampling---flow injection analyzer (CMS-FIA) for on-line monitoring of THM and HAA concentrations in drinking water. The chemical basis of the method is the reaction of the halogenated DBPs with nicotinamide in basic solution to form fluorescent products. Optimization studies, MDL, accuracy, and precision studies were conducted and concluded to be satisfactory for further adaptation of the CMS-FIA analyzer to on-line monitoring in drinking water.;A major part of this research was designed to evaluate the CMS-FIA as an analyzer for on-line monitoring studies. The results of side-by-side monitoring studies in Memphis, TN and Houston, TX compared the CMS-FIA method to USEPA Method 502.2 and USEPA Method 552.3. The results indicated that the CMS-FIA method could successfully be used for on-line monitoring of halogenated DBPs, with the advantage of providing data in near-real-time.;Additional research was devoted to better understand the chemistry of the reaction between the DBPs and nicotinamide. A detailed study of the rate law and mechanism enhanced the understanding when the CMS-FIA method can be applied and when it cannot. The rate law studies were carried out for the reaction of nicotinamide with the DBP species under the conditions of the analysis.