Flow Injection Analysis on Extraction of Trace Metal Ions with Mixed Solvents

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The present research was carried out in order to obtained the fundamental and important informations for the development of new flow injection analysis on solvent extraction. We had the following informations.1. Evaluation of a non-halogenated mixed solvent in the extraction of a complex(extractability, phase-separating ability)Taking account of the sensitivity and stability of metal complex and the selectivity in the extraction of the complex, pyridylazonaphthol-sulfonic acid system was selected. In addition to the selectivity on the basis of the partition equilibrium, the formation reaction of anionic metal complex in the aqueous phase enhances the selectivity of the extraction of metal ions. Up to this time, halogenated solvents such as chloroform have been exclusively used for ion association extraction. From the point of view of the ecopolicy, these solvents are undesirable for use. These solvents should be controlled regarding their use as much as possible. Then, some alternative … More s to these solvents were examined with copper (II) -PAN-S system, and it was found that 1-ocatnol/octane mixed solvent could be expected to have good extractability and good phase-separating ability. In addition, it was clarified that the partition of ion associate could be controlled by changing the mixing ratio of these solvents.2. Evaluation of complexing agent on the selective extraction of metal ions (use of HPLC)The formation constants of ion associates in the aqueous phase and their partition constants, which were scarcely determined so far, could be estimated by an detailed analysis of extraction equilibrium for the copper (II)-PAN-S system. The assessment of each complexing agent was achieved on HPLC systems from the point of the correlation between the partition constants of ion associates in the liquid-liquid partition and their capacity factors in HPLC.In the partition of ion associates for iron, cobalt, nickel, and copper complexes with a few kinds of pyridylazo compounds to the reversed-phase stationary phase, copper and cobalt complexes in the PAN-S systems were hardly retained even under the presence of a counter ion, and the partition of these ion pair was found to be markedly lower than that of iron and nickel complexes. The useful flow injection analysis syatem on the extraction of a metal complex is expected to be developed by a combination of these reagents and the mixed solvents described above. Less