This standard specifies methods for the determination of calcium content in tungsten powder, tungsten bar, tungsten trioxide, blue tungsten, purple tungsten, tungsten carbide, tungstic acid, ammonium paratungstate and ammonium metatungstate. Applicable to samples with calcium content ranging from 0.0003% to 0.050%. During the determination, the sample is analyzed by using hydrogen peroxide, ammonia water or citric acid, followed by the detection of calcium content on the Inductance Coupled Plasma Atomic EmissionSpectrometer. The standard requires the use of analytical pure reagents and secondary distillation water to ensure the accuracy of the measurement results.