Analytical Sciences

A Rapid and Sensitive Extractive Spectrophotometric Determination of Copper(II) in Pharmaceutical and Environmental Samples Using Benzildithiosemicarbazone

B. K. REDDY,* J. R. KUMAR,* K. J. REDDY,* L. S. SARMA,** and A. V. REDDY* 

*Analytical Division, Department of Chemistry, Sri Venkateswara University, Tirupathi-517502, India
**Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

Benzildithiosemicarbazone (BDTSC) is proposed as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of copper(II). BDTSC reacts with copper(II) in the pH range 1.0 - 7.0 to form a yellowish complex. Beer's law is obeyed in the concentration range 0.5 - 0.4 ug cm^-3. The yellowish Cu(II)-BDTSC complex in chloroform shows a maximum absorbance at 380 nm, with molar absorptivity and Sandell's sensitivity values of 1.63 x 10⁴ dm³ mol^-1 cm^-1 and 0.00389 ug cm^-2, respectively. A repetition of the method is checked by finding the relative standard deviation (RSD) (n = 10), which is 0.6%. The composition of the Cu(II)-BDTSC complex is established as 1:1 by slope analysis, molar ratio and Asmus' methods. An excellent linearity with a correlation coefficient value of 0.98 is obtained for the Cu(II)-BDTSC complex. The instability constant of the complex calculated from Edmond and Birnbaum's method is 7.70 x 10^-4 and that of Asmus' method is 7.66 x 10^-4, at room temperature. The method is successfully employed for the determination copper(II) in pharmaceutical and environmental samples. The reliability of the method is assured by analyzing the standard alloys (BCS 5g, 10g, 19e, 78, 32a, 207 and 179) and by inter-comparison of experimental values, using an atomic absorption spectrometer.

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