Chemical modifiers for controlling interferences in the flame atomic absorption spectrometric determination of chromium(III) and chromium(VI) and their separation
Abstract
The interfering effects of a range of organic and inorganic species on the atomic absorption signals of CrIII and CrVI were investigated. Such effects were eliminated by adding 20 mmol l–1 butylamine (BA) or N-cyanoacylacetaldehyde hydrazone (CyAH), as a chemical modifier, to both the sample and standard solutions. The role of BA was extended to separate CrIII from CrVI in admixture, with 100% recovery, using oleic acid as a surfactant at a pH of 5.5 ± 0.2. A mechanism for Cr atom population in the flame in the presence and absence of concomitants is suggested. Also, the role of BA or CyAH in eliminating interferences was investigated. The flotation mechanism is discussed. A simple, sensitive and rapid procedure for the separation and determination of CrIII from aqueous solutions was elaborated. The method was applied to the determination of CrIII in some complexes.