Because the organics in raw water that are detected using UV254 are often also the cause of color, color analysis is often used for the same purpose. However, the issue with color analysis is that many organics do not reflect in the visible light spectrum (causing low readings) and there are many color-causing substances (such as manganese) that aren’t relevant for organic analysis (causing high readings).
UV254 instruments are also useful for monitoring disinfection by-products (DBPs) as they are more sensitive to the aromatics which can react with chlorine to form them. This is another advantage over color analysis and is particularly useful in coagulation control.