Aspartic acid composition, polysuccinimide composition, polyaspartic acid composition, and cross-linked polyaspartic acid composition

An asparaginic acid composition containing asparaginic acid and an impurity, the impurity containing at least one substance selected from the group consisting of amino acids other than asparaginic acid, organic acids, and salts thereof, and the content of the impurity being 0.02-1.1 mass%. Also provided is a method for producing polysuccinimide, which comprises a step for carrying out a polymerization reaction of the aforementioned asparaginic acid using the aforementioned asparaginic acid composition. Further, a polysuccinimide composition, which is produced by the method for producing the polysuccinimide, is provided. 一种天门冬氨酸组合物，其包含：天门冬氨酸和杂质，前述杂质包含选自由除天门冬氨酸以外的氨基酸、有机酸、和它们的盐组成的组中的至少1种，前述杂质的含量为0.02质量％以上且1.1质量％以下。另外，一种聚琥珀酰亚胺的制造方法，其包括如下步骤：使用前述天门冬氨酸组合物，进行前述天门冬氨酸的聚合反应。另外，一种聚琥珀酰亚胺组合物，其是通过前述聚琥珀酰亚胺的制造方法而制造的。