A 3D printed chemiluminescence detector for the FIA determination of free available chlorine in concentrated chlorine dioxide solutions

Chlorination is the most widely used and cost-effective method for disinfecting drinking water worldwide. Unfortunately, this approach leads to the formation of disinfection by-products (DBPs), which have been shown to increase the potential for cancer and other health issues. To minimize DBPs, many water treatment plants have turned to alternative disinfectants such as chlorine dioxide (ClO₂). However, there have been reports of DBP formation when using ClO₂ due to free available chlorine (FAC) contamination. A suitable method is needed to determine the FAC content in concentrated ClO₂ solutions. This research addresses this need by focusing on the development of a simple flow-injection analyzer with a 3D printed chemiluminescence detector (FIA-3DCL). A gas-diffusion membrane module was used to isolate FAC from a quenched ClO₂ solution, then react it with lophine reagent to produce chemiluminescent light. The analytical performance of the FIA-3DCL system was evaluated by performing calibration, method detection limit, accuracy, and precision studies. Three calibration data regression techniques were compared, with the logarithmic fit having the best results. Following these studies, commercially available ClO₂ solutions were analyzed for FAC and used in spiking studies. Overall, the system provides a straightforward and automated method for determining μg L^-1 levels of FAC in solutions with g L^-1 levels of ClO₂.