Recent Advances of the Asymmetric Bisazo Derivatives of Arsenazo and Phosphonazo as Chromogenic Reagents in Analytical Chemistry

Abstract

The asymmetric bisazo derivatives of Arsenazo and Phosphonazo have been widely used as chromogenic reagents in spectrophotometric determination of thorium, uranium, rare earth elements and other heavy metals. They exhibit advantages over the symmetric reagents such as Arsenazo m and Chlorophosphonazo III both in sensitivity and selectivity. The following is a brief introduction and short review on these reagents concerning their structures, analytical characteristics, synthesis, purification and application. 182 references mainly published in the past decade are presented.