Abstract
The effective concentration of heavy metals present in ppb level in aqueous sample is performed by the extraction into diisobutyl ketone (DIBK) using ammonium pyrrolidinedithiocarbamate (APDC). DIBK is far less soluble in water compared to methyl isobutyl ketone or butyl acetate usually used in the solvent extraction-atomic absorption system and enables to concentrate trace metals up to 100 times. Various heavy metals are able to be extracted simultaneously with APDC at a wider pH range (1.5 to 6.0) than with the other chelating agents such as sodium diethyldithiocarbamate, 8-hydroxyquinoline, cupferron, and potassium butylxanthate. The results are as follows: (1) The calibration curves are linear up to 0.4μg Cd/ml(DIBK), 1.0 μg Cu/ml (DIBK), and 2.0 μg Pb, Ni, Co, Fe/ml(DIBK). (2) The coefficients of variation (%, n=10) are 2.7 for 0.5 μg Cd, 0.5 for 4.0 μg Cd; 3.0 for 2.0 μg Cu, 0.6 for 10.0 μg Cu; 6.5 for 2.0 μg Pb, 0.9 for 20.0 μg Pb; 3.5 for 2.0 μg Ni, 0.9 for 15.0 μg Ni; 3.1 for 2.0 μg Co, 0.8 for 20.0 μg Co; and 8.9 for 2.0 μg Fe, 1.2 for 15.0 μg Fe. (3) The 1 % absorbances for Cd, Cu, Pb, Ni, Co, and Fe are 0.16 ppb, 0.5 ppb, 1.2 ppb, 0.8 ppb, 0.8 ppb, and 0.8 ppb, respectively. (4) Recoveries of all these metals for the samples of river water, sea water, and effluent of treated sewage are satisfactorily good as high as 95 %.
