ADSORPTIVE STRIPPING ANALYSIS OF THIOCYTOSINE AT THE STATIC MERCURY-ELECTRODE SURFACE

The cathodic adsorptive stripping method has been applied for the trace determination of thiocytosine (Tcyt) using differential pulse voltammetry at the HMDE. The strong interaction of Tcyt with the mercury electrode surface leads to the formation of an adsorbed film of Hg(II)-thiolate complex at the electrode surface. The formation of this film is followed by cyclic DC- and differential pulse voltammetry. It has been found that formation of such film depends on various parameters, e.g. pH, concentration, adsorption time and adsorption potential. The influence of these parameters on the shape and the peak height of the cathodic stripping peak during the negative scan of potential has been determined. The influences of anions (SO4(2-), Cl-, ClO4-, NO3-) and cations [Cu(II), Ni(II), Pb(II) and Cd(II)] on the method of analysis are considered. The calibration curve for the determination of Tcyt is linear and the detection limit is 1.49 x 10(-8) mol/l, whereas in the presence of Cu(II) the method is developed and the detection limit for Tcyt determination is lowered to 4.99 x 10(-9) mol/l. A statistical analysis of the calibration curve data is included.