Total Carbon & Nitrogen Test

Method Description

Total nitrogen is determined using a combustion instrument operating on the Dumas principle. This method is universal for the determination of nitrogen content and can be used for nearly all food products. Pure oils and shortenings may cause fires in the instrument and should be assayed by the Kjeldahl method. The sample is completely combusted at high temperature in the presence of pure O2 (99.9%). Combustion products are H2O, CO2, NOx, and N2. Water vapor, oxygen, and CO2 are removed from the resulting gas stream by a series of thermoelectric coolers and chemical sorbents. NOx is reduced to N2 when passed through a hot column packed with copper. The resulting N2 is passed to a thermal conductivity detector, where it is quantified using helium as the carrier gas.