Comparison of Dumas and Kjeldahl methods for determination of nitrogen in feces.

The present study was undertaken to compare the nitrogen content of human feces as determined by the Kjeldahl technic and the micro-Dumas method as utilized in the automated Coleman nitrogen analyzer. The standard deviation between duplicate determinations of the same sample was 0.06% nitrogen in the case of the nitrogen analyzer and 0.02% nitrogen for the Kjeldahl method. The standard deviation between the average values obtained by each method for each sample was 0.07% nitrogen. The agreement between the two methods seemed to be independent of the nitrogen content. The apparent recovery of nitrogen by the nitrogen analyzer was found to be greater than that recovered by the Kjeldahl procedure. Factors which may be involved in this difference in recovery between the two methodsare discussed.