GB/T 12690.6-2017 Chemical analysis methods for non-rare earth impurity of rare earth metals and their oxides—Part 6: Determination of iron content—Kslium thiocyanate, 1,10-Phenanthroline spectrophotometric method
2018GB/T 12690.15-2018 Chemical analysis methods for non-rare earth impurities of rare earth metals and their oxides―Part 15: Determination of calcium content
2017GB/T 12690.6-2017 Chemical analysis methods for non-rare earth impurity of rare earth metals and their oxides—Part 6: Determination of iron content—Kslium thiocyanate, 1,10-Phenanthroline spectrophotometric method
2006GB/T 12690.15-2006 Chemical analysis methods for non-rare earth metals and their oxide.Determination of calcium oxide content
2003GB/T 12690.6-2003 Chemical analysis methods for non-rare earth impurities of rare earth metals and their oxides-Determination of iron content-Kalium thiocyanate,1,10-phenanthroline spectrophotometric method
1990GB/T 12690.16-1990 Rare-earth metals and their oxides--Determination of calcium content--Flame atomic absorption spectrometric method