The TOC (Total Organic Carbon) is one of the most important composite parameters in the assessment of the organic pollution of water. Since it includes all carbon compounds as one mass, it is exactly defined and an absolute quantity. In general, the TOC is determined by oxidizing a water sample. The produced CO2 is detected and defined quantitatively. Oxidation may be done thermally at high temperatures, photochemically using UV-persulfate method or chemically by the action of strong oxidants such as ozone.