Analytical Sciences

Differential Pulse and Square-WaveCathodic Stripping Voltammetry of Xanthine and Xanthosine at a MercuryElectrode

Y. M. TEMERK, M. M. KAMAL, G. A.-W.AHMED, and H. S. M. IBRAHIM

Chemistry Department, Assiut University,Assiut, Egypt

The surface activity of xanthine (Xan) andxanthosine (Xano) at a hanging mercury drop electrode (HMDE) was studiedusing out-of-phase ac and cyclic dc voltammetry. The results show that Xanand Xano were strongly adsorbed and chemically interacted with the chargedmercury surface, which is the prerequisite step for applying the cathodicadsorptive stripping voltammetric determination of such biologicallyimportant compounds. Differential pulse cathodic adsorptive strippingvoltammetry (DPCASV) and square-wave cathodic adsorptive strippingvoltammetry (SWCASV) were applied for the ultratrace determination of Xanand Xano compounds. Moreover, a rapid and sensitive controlled adsorptiveaccumulation of Cu(II) complexes of both compounds provided the basis of adirect stripping voltammetric determination of such compounds to submicromolar and nanomolar levels. Operational and solution conditions for the quantitative ultratrace determination of Xan and Xano were optimized inabsence and presence of Cu(II). The calibration curve data were subjectedto least-squares refinements. The effects of several types of inorganicand organic interfering species on the determination of Xan or Xano wereconsidered.

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