The total protein amount is important information for quality control and protein values for the food and feed industry along with research facilities.
The most efficient way to find the Nitrogen/Food Protein values is the Dumas Method which combusts samples using a high-temperature furnace in an oxygen rich environment. The Dumas method is much easier to use, faster and fully automated compared to the Kjeldahl method. Also, as with Kjeldahl, it does not give a measure of true protein which requires different correction factors to obtain a correct value.
Dumas nitrogen determination requires well-homogenized samples, heated in a high-temperature furnace where the combustion takes place rapidly at over 1000 °C in the presence of pure oxygen. This produces mostly water, carbon dioxide and nitrogen as well as several oxides (NyOx). This gas mixture (most water is removed) is passed through a reduction chamber containing copper heated to around 650 °C. This converts nitrogen oxides into elemental nitrogen and collects the oxygen in excess. Different traps remove the residual water and carbon dioxide. Total nitrogen content is measured by a thermal conductivity detector.