Nitrogen determination according to Kjeldahl
The procedure determines nitrogen and proteins in organic material. With the Kjeldahl process, the boiling point of sulfuric acid of 337 degrees Celsius is increased with the aid of catalysts. About 380 degrees is the optimum digestion temperature for organic material in sulfuric acid. The protein content is determined by multiplying the analytically determined nitrogen content with factor 6.25, for wheat, and flour with factor 5.7. With the Kjeldahl process, the nitrogen content is determined in 4 stages.