塩化セチルピリジニウム,オキシン誘導体共存下にメチルチモールブルーを用いる亜鉛(II),カドミウム(II)の吸光光度定量

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Zinc(II) or cadmium(II) rapidly forms a mixed complex with methylthymol blue(MTB), cetylpyridinium chloride(CPC) and 5-nitroso-8-quinolinol (N0-oxine) {for zinc(II)} or 2-methyl-8-oxine (CH_3-oxine) {for cadmium(II)} in a weak basic medium. The absorbance of the cadmium(II) complex at 630 nm (λ_<max>) and that of the zinc(II) complex at 620 nm (λ_<max>) were constant over the pH range from 7.6 to 9.0 for 3 h. The molar ratio of metal, MTB, oxine derivative and CPC in the mixed complex was a 1:1:2 by Job's method and the molar ratio method. The calibration curves were linear up to 4.0 μg/ml of cadmium(II) and 3.0 μg/ml of zinc(II). Sandell's sensitivity was 0.005 μg/cm^2 for cadmium(II) and 0.003 μg/cm^2 for zinc(II). The recommended procedure is as follows : To a sample solution containing<40 μg of cadmium(II) {or<30 μg of zinc(II)}, 0.5 ml of 1.0 × 10^<-2> M CPC, 0.25 ml of 1.0 × l0^<-2> M NO-oxine (or CH_3-oxine solution), 2.0 ml of a borate buffer (pH 8.2) and 1.0 ml of 1.0 × l0^<-3> M MTB were added. The mixture was diluted to l0.0 ml with water. After the solution was kept at (20〜25)℃ for 5 min, the absorbance was measured at 630 nm {for cadmium(II)} or at 620nm {for zinc(II)} against a reagent blank. Nickel(II), cyanide, sulfide and thiocyanate interfered. Aluminum (III) and thorium (IV) could be masked with sodium fluoride, and mercury(II) with l-ascorbic acid.
社団法人日本分析化学会の論文
1980-10-05