Photometric titrations of metal ions based on UV absorption of Bi(III)-EDTA

Abstract

The Bi-EDTA chelate absorbs strongly in the UV (λ max=263 nm;ɛ=103 l. mole−1. mm−1) in a wavelength region where most other metal chelates, metal ions and EDTA absorb to a much smaller extent or not at all. Two applications of this phenomenon are described:the determination of Bi(III) at the 10−5 M level in the presence of other metals, and the use of bismuth(III) as a back-titrant in the determination of traces of iron.