1994GB/T 223.18-1994 Methods for chemical analysis of iron steel and alloy.The sodium thiosulfate separation iodimetric method for the determination of cupper content
1982GB 223.18-1982 Chemical analysis of iron,steel and alloy--The determination of copper by thiosulfate-iodide method
GB 223.18-1982 Chemical analysis of iron,steel and alloy--The determination of copper by thiosulfate-iodide method was changed to GB/T 223.18-1994 Methods for chemical analysis of iron steel and alloy.The sodium thiosulfate separation iodimetric method for the determination of cupper content.