Abstract: Amino-c acid chlorphosphonazo synthesized in our laboratory reacts with both RE and Sc to form colored complexes. The spectra of these complexes are obviously different in their shapes. This paper demonstrates a DWS method to determine the amount of RE (λ₂ = 673.0nm; λ₁ = 689.5nm ) and Sc ( λ₂ = 626.0nm; λ₁ = 656.0nm ) respectively in their compounds. The maximum relative error is 12%. The weight ratio of two oxides are from 1:10 to 10:1.