The ISO 9198:2020 standard specifies methods for the determination of water-soluble sulfate content in paper, Cardboard and pulp, applicable to all types of pulp, paper and Cardboard. The standard provides two methods: weight method and Ion chromatography. The weight method is suitable for samples with water-soluble sulfate content in the range of 0.01% 1.0%, and Ion chromatography is suitable for samples with content in the range of 0.0005% 0.1%. The lower limit of determination is 20 mg sulfate ion per kilogram of dry sample. The standard provides a uniform detection method for the paper industry, which helps to evaluate the mass and chemical Stability of paper and Cardboard, especially in the fields of archival preservation, food Encasement, etc. It is of great significance.