Synthesis of new reagent fluoroarsenazo-DBN and the study on its chromogenic reaction with rare earths,thorium and bismuth

A new reagent fluoroarsenazo-DBN was synthesized and refined.Conditions of its chromogenic reaction with rare earths,thorium and bismuth were optimized.The complexes of rare earths with the reagent had maximum absorption at about 628nm and the apparent molar absorptivities were e Ce = 1.29× 10 5L·mol -1 ·cm -1 and e Y=1.30×10 5L·mol -1 ·cm -1 .Beer′s law was obeyed for rare earths in the range of 0～25μg/25mL.The apparent molar absorptivities of the other two complexes were e Th = 1 33×10 5L·mol -1 ·cm -1 and e Bi =1.23×10 5L·mol -1 ·cm -1 reapectively,Beer′s law was obeyed for Th(Ⅳ) in the range of 0～ 26μg/25mL and for Bi(Ⅲ) 0～35μg/25mL.This method has been used to determine trace Ce(Ⅲ) in noular cast iron and Bi(Ⅲ) in compound bismuth aluminate tablets with satisfactory results.