This document specifies the requirements, test methods, inspection rules, marking and accompanying documents, packaging, transportation and storage of ammonium sulfate, a by-product of D-hydroxyphenylglycine methyl ester. This document is applicable to the ammonium sulfate solution produced in the production process, splitting process and esterification process of mixed p-hydroxyphenylglycine, and the sulfuric acid by-product of D-p-hydroxyphenylglycine methyl ester obtained through extraction, decolorization, concentration and centrifugation, etc. Ammonium is mainly used in municipal greening, rare earth mining, leather deliming agent, etc.