1994GB/T 223.22-1994 Methods for chemical analysis of iron ,steel and alloy.The nitroso-R-salt spectrophotometric method for the determination of cobalt content
1982GB 223.22-1982 Chemical analysis of iron,steel and alloy--The determination of cobalt by the nitroso-R salt photometric method
GB 223.22-1982 Chemical analysis of iron,steel and alloy--The determination of cobalt by the nitroso-R salt photometric method was changed to GB/T 223.22-1994 Methods for chemical analysis of iron ,steel and alloy.The nitroso-R-salt spectrophotometric method for the determination of cobalt content.