Time of hydrolysis and acid concentration for fractionation of organic nitrogen

Abstract

Time of hydrolysis (3, 6,12, 20, 24, and 36 h) and acid concentration (HCl 1N, 3N, and 6N) were evaluated for recovering of N from known organic compounds and from soil by means of continuous and step-wise hydrolytic methods. High molecular weight polymers, like chitin, required more than 36 h for complete hydrolysis. Higher glucosamine decomposition was attained as time of hydrolysis increased, resulting in increasing amounts of amide fraction. There was a little decomposition of glucosamine to ammonium when hydrolysis was carried out with HCl 1N for 3 h, though chitin was partially hydrolyzed to glucosamine. N-amide was completely recovered using HCl 1N/3 h, HCl 3N/3 h, HCl 6N/4 h, as well as HCl 6N/20 h. Twelve hour hydrolysis was not enough to completely degrade high molecular weight polymers in continuous hydrolysis, though there was a degradation of amino sugars. The data emphasize the requirement of using more than one hydrolysis with different times and acid concentrations to better characterize the organic nitrogen fractions occurring in the soil.