Automatic total nitrogen analysis in nutritional evaluations using a block digestor

Experience obtained from more than 4 yr of using a block digestor in automatized total nitrogen analysis of various types of specimens (biological specimens, e.g., blood, urine, faeces, foods and feeds, protein concentrates) which are relevant in nutrition research is described. Results obtained on analysis of reference samples of casein during 1971-1974 revealed good reproducibility, although the samples were analysed over the 4 hr period and by different persons. The accuracy of the method in comparison with other methods was found to be remarkably good. The method allows rapid (in comparison with the Kjeldahl method) automatic analysis by the same setup for various specimens of interest in nutritional research with good accuracy.