Abbreviation for "Dissolved Organic Carbon", the concentration of dissolved, organically bound carbon in water (stated in mg/l).
The laboratory method used for determining DOC is not suitable for continuous measurement. Many studies have confirmed, however, that a reproducible correlation exists between DOC and absorption in the ultraviolet range. It has now become common practice to use this simple method, which is suitable for direct process measurement, for monitoring surface water, wastewater, and the efficiency of activated charcoal filters. Elimination of window contamination by using the Sigrist free-fall flow cell and the compensation of turbidity with the dichromatic method have contributed substantially to the widespread adoption of this measurement method.
The following Figure shows the correlation between UV absorption at 250 nm and the DOC in Rhine River water at Karlsruhe. (H. Sontheimer/W. Weindel, "Application of summary parameters in the determination of organic substances in water, with special emphasis on UV extinction".)