Study on Chromogenic Reaction of Cerium Subgroup Rare Earths with Antipyrylazo III

Chromogenic reaction of cerium subgroup rare earths with antipyrylazo Ⅲ was studied.The results show that in hydrochloric acid media of pH=2,antipyrylazo Ⅲ reacted with cerium subgroup rare earths to form a 4∶1 blue complex,λ_max=720 nm,e=8.015×10~4 L·mol~-1·cm~-1,Beer′s law was obeyed in the concentration range of 0～1.2 mg/L for rare earths elements.Antipyrylazo Ⅲ showed good selectivity.The method has been used for the spetrophotometric determination of cerium subgroup rare earths in synthesised sample with satisfactory results.