DIFFERENTIAL-PULSE VOLTAMMETRIC DETERMINATION OF COPPER(I) ION WITH ARUBEANIC ACID-MODIFIED CARBON-PASTE ELECTRODE

A copper(I) ion-sensitive modified electrode was constructed by incorp orating rubeanic acid into a carbon paste mixture composed of graphite powder and Nujol oil. By simple immersing of the modified electrode i nto the measuring solution, the test ion was chemically deposited oil the electrode via a complex formation. The: resulting surface was char acterized by cyclic voltammetry and differential pulse voltammetry. Th e exposure of the used modified electrode to a 0.1 M nitric acid and t he potential cycling, beyond more positive and negative potential than the redox potential of the copper complex led to the reuse of the ele ctrode more than three times. A linear calibration plot was obtained o ver the concentration range of 5.0X10(-6) to 1.0X10(-7) M with 5.6% re lative standard deviation. The detection limit for Cu(I) ion are found to be 5.0X10(-8) M using differential pulse voltammetry at 15 min oi tile deposition. Ag(I), and Fe(II) ions did not interfere. Alter the r eduction of Cu(II) ion to Cu(Ii with hydroxylamine in the sample solut ion, satisfactory results were obtained for the determination of coppe r in the certified standard urine reference material, SRM'S 2670 (trac e elements in the urine).