No abstract

The most generally used method for the determination of preformed ammuonia in plant material is the aspiration of a sample with Ca(OH)2, MgO, or 52 per cent. K2C03. This technique was shown to include other than preformed ammonia nitrogen (4) for, with prolonged aeration, there was a continual evolution of ammonia, owing to the presence of unstable nitrogen compounds. PUCHER (3) reported that this was caused by the presenee of amides. This error was obviated in plant juice by the removal of ammonia by permutit, washing free from excess juice, treating with NaOH, and aspirating in the Van Slyke-Cullen ammonia apparatus. CHIBNALL and WESTALL (1) and VICKERY, et al. (5), have slhown that it is possible to determiine glutamine and asparagine amide nitrogen in a mixture of the two amides by choosing the proper conditions for hydrolysis. In an attempt to collect a number of methods into a system for the analysis of plant juice it was thought worthwhile to study the adsorption of amides by permutit, and to reinvestigate the use of permutit for the determination of amiuionia. Determination of ammonia The action of 52 per cent. K2C03 on plant juice under continued aeration causes a breakdown of the amides present. A typical curve for this, using beet juice, is shown in figure 1 (curve D), the break coming at the end of two hours. An attempt was made to simulate this curve with a synthetic solution of the following composition: 0.0812 mg. NH3-N, 1.5 mg. asparagine amide-N, 0.959 mg. glutaminie amide-N anid 1 ml. buffer2 per 5-inl. sample. In figure 1, each curve, excepting curve D, represents the effect of aeratingt this mixture or variations of it, lacking glutamine or asparagine or both, wiith 10 ml. of 52 per cent. K2CO, for varying periods. A study of these 1 Published by permission of the Director as Contribution No. 563 of the Rlhode Island Agricultural Experiment Station. 2 Modified buffer (2) 7 parts 0.1 N KHIP04 l274 l 1 part 0.1 N K2HPO4 2 ml. M/3 sodium malate 2.17 ml. Glucose 1.00 gr. Water dilute to 15.0 ml.

No abstract

No abstract

When subjected to alkaline aeration at pH 11.0, the complex is hydrolyzed and the liberated ammonia so isolated is a measure of the amount of a-amino nitrogen that was originally present in the solution.