A comparison of nitrogen values obtained utilizing the Kjeldahl nitrogen and Dumas combustion methodologies (Leco CNS 2000) on samples typical of an animal nutrition analytical laboratory

The Dumas combustion procedure using Leco's CNS 2000 analyzer has been shown to give nitrogen values comparable to those obtained with the Kjeldahl procedure for soil and plant products (slightly higher for most samples). These procedures were compared for a range of samples more typical for an animal nutrition laboratory (feed, excreta, carcass, egg yolk, milk and urine), For the 36 samples compared, the Kjeldahl procedure gave N values slightly lower than the Dumas procedure: N-Kjeldahl = 0.0103 + 0.9855 x N-CNS.The coefficient of variation for standard AAFCO broiler and cattle feeds (measured repeatedly over an 18-month period) were 2.23 (n = 90) and 2.12 g/100 g (n = 177), respectively. It was concluded that the Dumas combustion procedure is capable of replacing the Kjeldahl procedure for routine animal nutrition laboratory N analyses. The Dumas procedure has the advantages of using fewer strong reactants, requiring less labor, and uses a more efficient temperature to release the nitrogen from the samples than the Kjeldahl procedure. (C) 1998 Elsevier Science B.V.