Total Nitrogen - Dumas Method

This technique uses a LECO FP-528 Nitrogen Analyzer to determine total N in soil materials. A 250-300 mg sample is weighed into a capsule and dropped into an 850o C furnace purged with O2 gas. The combustion products of CO2, H2O and NOx are filtered, cooled by a thermoelectric cooler to condense most of the water, and collected in a large ballast. A 3 cc aliquot of the ballast combustion products is integrated into a He carrier stream and passed through: 1.) a hot copper column where the O2 is removed and the NOx gasses are converted to N2 and 2.) a reagent tube which scrubs the CO2and remaining H2O from the stream. The N2content is then measured by a thermal conductivity cell against a He background and the result displayed as weight percentage of nitrogen.

(Ref. No. 62 and Ref. No. 63 - Method References)