DETERMINATION OF AMMONIA, GLUTAMINE, AND ASPARAGINE AMIDE NITROGEN IN PLANT JUICE

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Abstract
The amide N of asparagine and glutamine is hydrolyzed to NHs under the alkaline conditions found in the usual NH3 detn. To eliminate this error-producing reaction, plant juice is shaken with Na permutit, which adsorbs the NH3. 2-3 washings suffice to remove the amides from the permutit. NH3 is then detd. after aspiration by Nesslerization or titration. The amides are detd. by hydrolysis; glutamine, by heating plant juice in a boiling water bath for 2 hrs. in a buffer mixture (pH 6-6.5); total amides by heating in a similar manner for 3 hrs. in N H2SO4. The difference between total and glutamine amide N is assumed to be asparagine amide N. Juice proteins must be removed; in the presence of N H2SO4 they hydrolyze, giving off NH3.
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