Abstract
Conventional Kjeldahl analysis with modifications, Kjeltec analysis with block digestion and semiautomated distillation, and the Hach method for determining nitrogen (N) were compared using a wide range of samples. Twenty different sample types were ground and mixed. Each sample type was divided into 5 subsamples which were analyzed for N by each of the 3 methods. In each sample type, differences (P < 0.05) were detected among the 3 N determination methods in 5 of the 20 N sources analyzed. The mean N content over all 20 samples was higher with Kjeldahl analysis (P < 0.05) than with Kjeltec, while Hach analysis produced intermediate results. Results also indicated that the Hach procedure had the greatest ability to detect differences in N content among sample types, being more sensitive than either other method (P < 0.05).