Methods for the Determination of Submicro Quantities of Total Nitrogen, Ammonia, Amino Nitrogen, Amides, Peptides, Adenylic Acid, and Nitrates
نویسنده
چکیده
In 1935 one of us described micromethods for ammonia, urea, total nitrogen, uric acid, creatinine, and allantoin (1). These methods are adapted for the analysis of 1 to 2 ml. aliquots of dilute solutions, e.g. 0.1 mg. per cent of ammonia or urea, and for carrying out a large number of analyses simultaneously. These methods all end in a calorimetric measurement. In the present communication methods are described for the determination of submicro quantities of nitrogen in the form of ammonia, amino groups, amides, urea, total nitrogen (and by difference, protein nitrogen), peptides, adenylic acid, and nitrate. The aliquots used are 0.1 to 0.2 ml.; the minimum dilution may be somewhat lower than in the methods we described previously. Three innovations are introduced in these methods. One is a convenient glass electrode submicrotitration procedure. The problem here was to devise an electrical system which is rugged, quick recording, easy to operate, and from which electrical leaks are excluded. The Conway-Byrne ammonia distillation procedure (2) has been made more rapid. A Kjeldahl procedure has been devised which is simpler and more convenient than any of the preexisting methods for determining total nitrogen in submicro quantities. The same principle is also used in the determination of amides. In all of these new methods the final procedure is an electrometric titration with a glass electrode. This is more accurate, of wider application, quicker, and more convenient than the colori-
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