What does TOC stand for and how is it measured?

• A. Total Organic Carbon; burn sample at 550 C and measure CO2 produced
• B. Total Oxygen Content; measure with oxygen probe
• C. Total Organic Contaminants; solvent extraction
• D. Total Organic Carbonate; acid-base titration

Answer: (A)

Total Organic Carbon is a measure of the amount of organic carbon in a sample. To obtain the TOC, the organic matter is oxidized to carbon dioxide, and that CO2 is then measured. In the described method, the sample is combusted at about 550 C in the presence of oxygen, which efficiently converts organics to CO2. The produced CO2 is detected (commonly with an infrared detector) and reported as the TOC concentration. This approach focuses on the carbon portion of organic matter and yields a result in terms of carbon content.

Other options misidentify what TOC stands for or describe unrelated techniques. For example, measuring oxygen content with an oxygen probe doesn’t assess organic carbon, solvent extraction targets contaminants rather than carbon content, and carbonate-related titration addresses inorganic carbon, not organic carbon.