Determination of the Forms of Carbon in Geologic Materials

Total carbon was determined in 30 geological reference materials by combustion/IR and combustion/coulometry methods. The combustion/coulometric method does not require empirical calibration and was found to be more precise than the combustion/IR method despite the use of smaller sample sizes. Carbonate carbon was determined by coulometric titration of acid‐evolved CO2. Non‐carbonate carbon was calculated as the difference between the total and carbonate carbon contents.