The amide nitrogen content of gelatins

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Abstract
A rapid and convenient method for the determination of amide nitrogen in gelatin, based on preliminary hydrolysis with 2N hydro-chloric acid, is described. No significant decomposition, resulting in release of non-amide ammonia, occurs during the distillation stage. Errors resulting from the distillation of carbon dioxide have been decreased to a low level. The method of hydrolysis gives results very close to those obtained with 12N hydrochloric acid at 37[degree]. The amide contents of a series of deionized gelatins, ranging from pI 4.80 to 9.4, are related to their isoionic points by a curve of similar shape to the titration curve. Certain gelatins and glues that show evidence of containing polysaccharide impurities give rise to larger quantities of ammonia on hydrolysis than would be expected from their isoionic points.