Determination of ammonia, amides, and the degree of hydrolysis of partially hydrolyzed polyacrylamide by thermometric titration and direct injection enthalpimetry

Abstract

The properties of partially hydrolyzed polyacrylamide (PHPA) solutions are influenced by the degree of hydrolysis of the amide function. Solutions of PHPA usually contain ammonia and strong base left from the preparative hydrolysis reaction. Methods for determining the carboxyl function and ammonia by a thermometric titration with HCl, and the amide function by direct injection enthalpimetry with hypobromite are described in this paper. The data from both determinations on a given sample are combined to correct for interferences from ammonia in the amide determination and to make it unnecessary to know the total amount of polymer present in order to calculate the degree of hydrolysis. The determination with hypobromite is generally applicable to ammonia, amides which will undergo the Hoffman degradation reaction, and amines which can be oxidized by hypobromite. The detection limit is about 0.1 mM in all cases.