The ISO 9197:2016 standard specifies methods for the determination of water-soluble chlorides in paper, Cardboard and pulp, and is applicable to all types of paper, Cardboard and pulp. The standard uses the mercury nitrate method, the silver nitrate (AgNO3) potential Titrimetric method or Ion chromatography for detection, with a determination limit of 20 mg of chloride ions per kilogram of dry sample. The content of water-soluble chlorides affects the performance and mass of paper, so the standard provides an important test basis for quality control, production process optimization and environmental assessment in the paper industry.