エチレン-1,2-ビス(フェニルジチオカルバミン酸アンモニウム)による銅(II)の抽出-吸光光度定量

抄録

Diammonium ethylene-1, 2-bis(phenyldithiocarbamate) (DEP) reacts with copper(II) to form a waterinsoluble brown complex in aqueous solution in the pH range of 4.326.81, which can be extracted with chloroform. Based on the formation of the complex, an extraction-spectrophotometric method for determination of copper (II) has been developed. The recommended procedure is as follows: To a sample solution (5 cm³) containing copper(II), less than 20 μg was added 8 cm³ of Britton and Robinson buffer of pH 5.5, and then added 1 cm³ of 0.06 w/v % DEP-methanol solution. The copper(II) chelate formed in the solution was extracted with 5 cm³ of chloroform by shaking for 1 min. The absorbance of the organic phase was measured at 442 nm against the reagent blank. The apparent molar absorption coefficient of the complex was evaluated as 1.56 × 10⁴ dm^-3 mol^-1 cm^-1, and the calibration curve obeyed Beer's law over the concentration range from 0.1 μg cm^-3 to 4.0 μg cm^-3 of copper (II). The molar ratio of copper (II) to DEP in the complex was determined to be 1:2 by the continuous variation method. Various metal ions, such as cobalt(II), iron(II) and (III), lead(II), nickel (II), palladium(II), strontium(II), zinc(II), and so on, interfered. These interfering metal ions could be easily masked by EDTA.