Microanalysis of Nitrogen in Certain Pyrimidines by the Dumas Method

Abstract

micro-Dumas method of Pregl (S) has an enviable reputation for producing accurate results on a variety of substances. Properly handled, it was considered an accurate method for any organic nitrogen-containing compound.This method was used in this laboratory on a wide range of compounds without any known discrepancy until a certain series of pyrimidines of known purity failed to give the required amount of nitrogen. The nitrogen values obtained were from 0.4 to 2.0 per cent below theory and were reproducible under uniform treatment of the sample. The carbon and hydrogen values for these compounds agreed with the theoretical values within the limits of experimental error.Several papers have appeared recently in the literature in which references were made to the fact that there were certain types of compounds which could not be analyzed properly by the Dumas method. The nitrogen values ob-

Dumas Microdetermination of Nitrogen in Refactory Organic Compounds. Modification of Zimmermann's Method

“…A REVIEW of procedures for the Dumas microdetermination of nitrogen in refractory substances has shown the need for a simple method applicable to both tractable and refractory compounds. Some of the existing methods which claim excellent results (9,18) are not of general applicability-for instance, the potassium chlorate method of Spies and Harris (18) and the copper acetate method of Hayman and Adler (9) were applied to pteridines without success (1). Brancone and Fulmor (1) were able to analyze pteridines merely by raising the temperature of the movable burner to 900"C.; oxidation aids were omitted.…”

“…tional Dumas method: A carefully controlled combustion with painstaking observation of bubble speed is required, if accuracy and reproducibility are to be achieved ( 14). If the Dumas method is adapted to the analysis of refractory compounds by adding oxidation aids (7,9,18), the changes involved may cause inconsistent results, as some investigators have reported (1,8,10,17). Without certain modifications, however, refractory compounds, such as certain pyrimidines, purines, and pteridines, give extremely erratic results (1, 8-10, 12, 13, 17, 18).…”