This method quantitatively determines the total amount of organic carbon present in soil. The method involves pre-treating the sample with dilute acid to remove carbonate carbon and then analyzing for total carbon (TC) using an instrument that utilizes a combustion system with an induction furnace coupled with an IR detector system. This method is based on the oxidation of the sample by “flash combustion” which converts all organic and inorganic substances into combustion gases (N2, NOx, CO2, and H2O). If total inorganic carbon (TIC) is also requested, the sample is analyzed for TC without acid pre-treatment and the TOC value subtracted from the TC value yields the amount of TIC in the sample. The method has a detection limit of approximately 0.02% carbon. Sample material must be ground to a powder fine enough to pass through a 60 mesh screen (<0.25 mm).
Sample material must be ground to a powder fine enough to pass through a 60-mesh screen (<0.25 mm).
Sample amount requested: 5 g (Sample Amount Guide)
Please contact the Analytical Laboratory with questions concerning limited sample.
References:
Western Region Method S 9.30, Total Nitrogen and Organic Carbon – Combustion Method); Soil, Plant and Water Reference Methods for the Western Region, WREP-125, 4th Edition, 2013.
Leco Application Note 203-821-679, Determination to Total Carbon (TC) and Total Organic Carbon (TOC) in Soil by Acid Digestion and Combustion, Revision 1, April 2026.
