Metal complexing capacity of natural waters based on solvent extraction and reverse FIA.

ITABASHI Hideyuki

doi:10.2116/bunsekikagaku.44.989

Methods for the measurement of copper(II) complexing capacity (CuCC) of natural waters by using a back-extraction of bis(benzoyltrifluoroacetonate) copper(II) (Cu(bfa)₂) and the dithizone extraction rate of copper(II) complex were described. From the measurements of CuCC of river water samples, it was found that the CuCC of the water sample in the urban area was larger than that up-stream, due to a ligand originating from human activities. The conditional stability constant (β) of the resulting copper(II) complex was determined by using the back-extraction method.β values of river water samples were 10⁹10¹⁰ order of magnitude. Free copper(II) concentration of the Kiryu river was estimated by using the side-reaction coefficient in the extraction of copper(II) with tenoyltrifluoroacetone. The free copper(II) concentration was estimated to be 10^-13 mol dm^-3 which is 10^-5 of total copper. Most of the copper(II) in the river, therefore, is complexed with naturally occurring ligands. A procedure for the measurement of metal complexing capacity by using reverse flow injection analysis (r-FIA) system was also described. The applicability of the method was evaluated by measuring zinc(II), cadmium(II) and lead(II) complexing capacities of both river and lake waters. The values obtained by the r-FIA system were in the same order of magnitude as those obtained by the back-extraction method, indicating the usefulness of the r-FIA method for the estimation of complexing capacity.

Metal complexing capacity of natural waters based on solvent extraction and reverse FIA.

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