A 150 mg of ground soybean sample is weighed into a gel 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 CO2 and remaining H2O from the stream. The N2 content is then measured by a thermal conductivity cell against a He background and the result displayed as weight percentage of nitrogen.
(See Method References No. 60 and No. 61)