GB 6854-1986 specifies the technical specifications for the pH reference reagent phosphoric acid disodium hydrogen. It covers the core index requirements such as purity and ph value, and formulates strict inspection rules, including reasonable sampling procedures and judgment standards. At the same time, detailed test methods are given for the accurate determination of various indicators. The production and inspection of phosphoric acid disodium hydrogen according to this standard can ensure high accuracy as a reference reagent in the pH measurement system, providing a reliable traceability basis for chemical analysis, pharmaceutical research and development, environment monitoring and many other industries that rely on accurate pH determination.