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322

TOTAL ORGANIC CARBON-COMBUSTION METHOD

Summary

This analytical method quantitatively determines the total amount of organic carbon in soil.  The method involves pre-treating the sample with dilute acid to remove carbonate carbon and then analyzing for total carbon using an instrument that utilizes a combustion system with an induction furnace coupled with a thermal conductivity detector (TCD) system and an IR detector system. In cases of very limited sample amount, an alternative method maybe utilized. This method combines acid fumigation with a dynamic flash combustion system that is coupled with a gas chromatographic (GC) separation system and thermal conductivity detection (TCD) system.  Acid fumigation with hydrochloric vapor removes inorganic carbon with no loss of organic carbon. Both analytical methods are 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). The method has a detection limit of approximately 0.02% carbon

Sample material must be ground to a fineness of < 0.5 mm (60 mesh). 

Sample amount requested:  5

Questions concerning limited sample size can be answered by the UC Davis Analytical Laboratory

Harris, D., Horwáth, W. R.  and Van Kessel, C.  2001.  Acid fumigation of soils to remove carbonates prior to total organic carbon or CARBON-13 isotopic analysis.  Soil Science Society of America Journal 65:1853-1856 (2001.) 

AOAC Official Method 972.43, Microchemical Determination of Carbon, Hydrogen, and Nitrogen, Automated Method, in Official Methods of Analysis of AOAC International, 16th Edition (1997), Chapter 12, pp. 5-6, AOAC International, Arlington, VA.