DETERMINATION OF AMINO NITROGEN IN PLANT EXTRACTS

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Abstract
Treatment of plant extracts with neutral Pb acetate, decolorizing carbon, and solid CaO invariably resulted in a decrease of gas measured as amino N by the Van Slyke method. Evidence is presented supporting the validity of the method of low-temp. distillation with solid CaO under reduced pressure which resulted in maximum decrease in all cases. Acid derivatives of the phenols, as the tannins, react with HNO2 in the amino determination producing gases measured as N. This error is eliminated by distillation with CaO. Limits of error caused by the presence of ammonia are discussed. Reductions (6.1-84.9%) in gas measured as amino N were found in 12 tissues extracted with water and 80% alcohol after distillation with CaO. 5 plant fractions of normal and P-deficient tomato plants showed similar decreases of 26.4-42.9% after 10-months'' storage in alcohol. Alcoholic storage of tomato plant extracts resulted in marked increases in ammonia N and decreases in a-amino N. With 9 tissues 80% alcohol extracted an average of only 63.7% as much soluble non-protein N and 66.9% as much alpha-amino N as was removed with distilled water at 25[degree] C.