CHEMICAL MODIFIERS FOR CONTROLLING INTERFERENCES IN THE FLAME ATOMIC-ABSORPTION SPECTROMETRIC DETERMINATION OF CHROMIUM(III) AND CHROMIUM(VI) AND THEIR SEPARATION

The interfering effects of a range of organic and inorganic species on the atomic absorption signals of Cr-III and Cr-VI were investigated. Such effects were eliminated by adding 20 mmoll(-1) butylamine (BA) or N-cyanoacylacetaldehyde hydrazone (CyAH), asa chemical modifier, to b oth the sample and standard solutions. The role of BA was:extended to separate Cr-III from Cr-VI in admixture, with 100% recovery, using ole ic acid asa 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 i s suggested. Also, the role of BA or CyAH in eliminating interferences was investigated. The flotation mechanism is discussed, A simple, sen sitive and rapid procedure for the separation and determination of Cr- III from aqueous solutions was elaborated. The method was applied to t he determination of Cr-III in some complexes.