Determination of total carbon in soils by wet combustion

A digestion–purification train using sulphuric–phosphoric acid and potassium dichromate and employing a gravimetric finish is described for the determination of total organic carbon in soils. Interference of volatile mineral acids, chlorine and chromyl chloride (derived from chloride present in the soil) is prevented by using a bubbler containing a solution of sodium acetate, acetic acid and potassium iodide. The results obtained for total carbon in a number of mineral soils were very similar to those obtained by the Pregl dry combustion method.