Abstract.An electrochemical anodic stripping proce-dure for ultra-trace assay of xanthine in Cu 2þ solution at a glassy carbon electrode (GCE) is described. Cyclic voltammetry was used to characterize the nature of the process taking place at the GCE. The anodic stripping response in the presence of Cu 2þ , at 150 mV (peak I) and 600 mV (peak II), is evaluated with respect to various experimental and instrumental conditions. Voltammetric studies show that the mechanism of the overall reaction is similar to that of the oxidation of purine derivatives at a pyrolytic graphite electrode. It is found that the copper metal deposited onto the GCE was oxidized to Cu þ at around 180 mVvs. Ag=AgCl and the generated Cu þ reacted with xanthine to accumulate on the GCE as an insoluble compound. The Cu þ -xanthine compound accumulated on the GCE was redissolved by the oxidation of Cu þ to Cu 2þ at ca. 150 mV, and the concentration of xanthine in the vicin-ity of the GCE increased. The results enabled us to use the measurement of the oxidation peak current as the basis of a simple, accurate and rapid method of deter-mining xanthine within a concentration range of 19.9 to 166 nM for peak (I) and 0.24 to 17.2mM for peak (II). Promising results were obtained for xanthine determination by using an external mixing step prior to stripping measurements, which yielded a detection limit of 0.138mgL 1 (9.110 10 M) xanthine. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered

Abstract.An electrochemical anodic stripping proce-dure for ultra-trace assay of xanthine in Cu 2þ solution at a glassy carbon electrode (GCE) is described. Cyclic voltammetry was used to characterize the nature of the process taking place at the GCE. The anodic stripping response in the presence of Cu 2þ , at 150 mV (peak I) and 600 mV (peak II), is evaluated with respect to various experimental and instrumental conditions. Voltammetric studies show that the mechanism of the overall reaction is similar to that of the oxidation of purine derivatives at a pyrolytic graphite electrode. It is found that the copper metal deposited onto the GCE was oxidized to Cu þ at around 180 mVvs. Ag=AgCl and the generated Cu þ reacted with xanthine to accumulate on the GCE as an insoluble compound. The Cu þ -xanthine compound accumulated on the GCE was redissolved by the oxidation of Cu þ to Cu 2þ at ca. 150 mV, and the concentration of xanthine in the vicin-ity of the GCE increased. The results enabled us to use the measurement of the oxidation peak current as the basis of a simple, accurate and rapid method of deter-mining xanthine within a concentration range of 19.9 to 166 nM for peak (I) and 0.24 to 17.2mM for peak (II). Promising results were obtained for xanthine determination by using an external mixing step prior to stripping measurements, which yielded a detection limit of 0.138mgL 1 (9.110 10 M) xanthine. The effect of some interferences (e.g. purine compounds, amino acids and some metal ions) was considered

Square-wave cathodic adsorptive stripping voltammetry based on adsorptive accumulation is a very sensitive technique for the trace determination of xanthosine 5 0 -monophosphate (5 0 -XMP) and xantho-sine 5 0 -diphosphate (5 0 -XDP). The determination is based on the strong interaction of the adsorption of xanthosine phosphate compounds on a mercury elec-trode surface, forming Hg(II)-xanthate. The cathodic reduction of the accumulated Hg(II)-xanthate complex provides the basis for direct stripping measurements of the investigated biological compounds at sub-nanomolar concentration levels. Moreover, controlled adsorptive accumulation of the Cu(II) complex of xanthosine phosphate is also reported to assay trace amounts of xanthosine phosphate. The height of the sharp chelate peak of adsorbed Cu(II)-xanthate, coupled with the flat baseline, facilitates measurements at nanomolar and submicromolar concentration levels. The adsorption and the redox behaviour of the in-vestigated complexes are indicated by cyclic voltam-metry. Experimental and instrumental parameters for the quantitative determination were optimized. Statis-tical analysis of the calibration curve data is also included

Square-wave cathodic adsorptive stripping voltammetry based on adsorptive accumulation is a very sensitive technique for the trace determination of xanthosine 5 0 -monophosphate (5 0 -XMP) and xantho-sine 5 0 -diphosphate (5 0 -XDP). The determination is based on the strong interaction of the adsorption of xanthosine phosphate compounds on a mercury elec-trode surface, forming Hg(II)-xanthate. The cathodic reduction of the accumulated Hg(II)-xanthate complex provides the basis for direct stripping measurements of the investigated biological compounds at sub-nanomolar concentration levels. Moreover, controlled adsorptive accumulation of the Cu(II) complex of xanthosine phosphate is also reported to assay trace amounts of xanthosine phosphate. The height of the sharp chelate peak of adsorbed Cu(II)-xanthate, coupled with the flat baseline, facilitates measurements at nanomolar and submicromolar concentration levels. The adsorption and the redox behaviour of the in-vestigated complexes are indicated by cyclic voltam-metry. Experimental and instrumental parameters for the quantitative determination were optimized. Statis-tical analysis of the calibration curve data is also included

Square-wave cathodic adsorptive stripping voltammetry based on adsorptive accumulation is a very sensitive technique for the trace determination of xanthosine 5 0 -monophosphate (5 0 -XMP) and xantho-sine 5 0 -diphosphate (5 0 -XDP). The determination is based on the strong interaction of the adsorption of xanthosine phosphate compounds on a mercury elec-trode surface, forming Hg(II)-xanthate. The cathodic reduction of the accumulated Hg(II)-xanthate complex provides the basis for direct stripping measurements of the investigated biological compounds at sub-nanomolar concentration levels. Moreover, controlled adsorptive accumulation of the Cu(II) complex of xanthosine phosphate is also reported to assay trace amounts of xanthosine phosphate. The height of the sharp chelate peak of adsorbed Cu(II)-xanthate, coupled with the flat baseline, facilitates measurements at nanomolar and submicromolar concentration levels. The adsorption and the redox behaviour of the in-vestigated complexes are indicated by cyclic voltam-metry. Experimental and instrumental parameters for the quantitative determination were optimized. Statis-tical analysis of the calibration curve data is also included

Square-wave cathodic adsorptive stripping voltammetry based on adsorptive accumulation is a very sensitive technique for the trace determination of xanthosine 5 0 -monophosphate (5 0 -XMP) and xantho-sine 5 0 -diphosphate (5 0 -XDP). The determination is based on the strong interaction of the adsorption of xanthosine phosphate compounds on a mercury elec-trode surface, forming Hg(II)-xanthate. The cathodic reduction of the accumulated Hg(II)-xanthate complex provides the basis for direct stripping measurements of the investigated biological compounds at sub-nanomolar concentration levels. Moreover, controlled adsorptive accumulation of the Cu(II) complex of xanthosine phosphate is also reported to assay trace amounts of xanthosine phosphate. The height of the sharp chelate peak of adsorbed Cu(II)-xanthate, coupled with the flat baseline, facilitates measurements at nanomolar and submicromolar concentration levels. The adsorption and the redox behaviour of the in-vestigated complexes are indicated by cyclic voltam-metry. Experimental and instrumental parameters for the quantitative determination were optimized. Statis-tical analysis of the calibration curve data is also included

Abstract.Cathodic adsorptive stripping voltammetry (CASV) was applied for the determination of rutin in pharmaceuticals, human urine, and blood serum. An electrochemical stripping procedure for trace measure-ments of rutin was developed based on the adsorption of the Cu 2þ -rutin complex on a hanging mercury drop electrode and applied to the quantification of the drug. Cyclic voltammetry was used to characterize the inter-facial and redox behavior of the adsorbed Cu 2þ -rutin complex. Experimental and instrumental parameters for quantitative determination were optimized, and a detection limit of 4.910 9 molL 1 in presence of Cu 2þ-ions for quantification of rutin under optimum conditions was derived. The sharp peak of the adsorbed Cu 2þ -rutin complex associated with an effective inter-facial accumulation of this compound facilitates the determination of rutin in biological fluids with good recoveries. The degree of interference from potentially present metal ions and organic compounds on the CASV signal for Cu 2þ -rutin complex was evaluated.

Abstract.Cathodic adsorptive stripping voltammetry (CASV) was applied for the determination of rutin in pharmaceuticals, human urine, and blood serum. An electrochemical stripping procedure for trace measure-ments of rutin was developed based on the adsorption of the Cu 2þ -rutin complex on a hanging mercury drop electrode and applied to the quantification of the drug. Cyclic voltammetry was used to characterize the inter-facial and redox behavior of the adsorbed Cu 2þ -rutin complex. Experimental and instrumental parameters for quantitative determination were optimized, and a detection limit of 4.910 9 molL 1 in presence of Cu 2þ-ions for quantification of rutin under optimum conditions was derived. The sharp peak of the adsorbed Cu 2þ -rutin complex associated with an effective inter-facial accumulation of this compound facilitates the determination of rutin in biological fluids with good recoveries. The degree of interference from potentially present metal ions and organic compounds on the CASV signal for Cu 2þ -rutin complex was evaluated.

Flutamide (Flu) is a chemotherapeutic drug, used for the treatment of prostate cancer. It functions by interfering DNA in fast growing cells and preventing them from reproducing. The present work is focused on the interaction of Flu with single and double stranded DNA at different temperatures and at physiological pH 7.4 (human blood pH). Cyclic voltammetry, square wave voltammetry and UV–visible spectroscopy were used to analyze the interaction of Flu with DNA. The voltammetric results indicate Flu gets intercalated between dsDNA bases and the strength of interaction is independent on the ionic strength. The hyperchromic effect in absorption spectra of Flu-dsDNA complex affirmed the intercalative mode of binding between Flu and dsDNA. Comparison of the mode interaction of Flu with dsDNA and ssDNA was discussed. The binding constants, stoichiometric coefficients and thermodynamic parameters of Flu-dsDNA and Flu-ssDNA complexes were evaluated. The association between Flu and dsDNA is maximum at 308 K which depicts the most stable complexes are formed at near human body tempera-ture. The decrease in the peak current of Flu resulting from its interaction with DNA was employed for determination of dsDNA and ssDNA concentration. The detection limits of dsDNA and ssDNA were found to be 4.2710 7 M and 1.8710 7 M, respectively

Flutamide (Flu) is a chemotherapeutic drug, used for the treatment of prostate cancer. It functions by interfering DNA in fast growing cells and preventing them from reproducing. The present work is focused on the interaction of Flu with single and double stranded DNA at different temperatures and at physiological pH 7.4 (human blood pH). Cyclic voltammetry, square wave voltammetry and UV–visible spectroscopy were used to analyze the interaction of Flu with DNA. The voltammetric results indicate Flu gets intercalated between dsDNA bases and the strength of interaction is independent on the ionic strength. The hyperchromic effect in absorption spectra of Flu-dsDNA complex affirmed the intercalative mode of binding between Flu and dsDNA. Comparison of the mode interaction of Flu with dsDNA and ssDNA was discussed. The binding constants, stoichiometric coefficients and thermodynamic parameters of Flu-dsDNA and Flu-ssDNA complexes were evaluated. The association between Flu and dsDNA is maximum at 308 K which depicts the most stable complexes are formed at near human body tempera-ture. The decrease in the peak current of Flu resulting from its interaction with DNA was employed for determination of dsDNA and ssDNA concentration. The detection limits of dsDNA and ssDNA were found to be 4.2710 7 M and 1.8710 7 M, respectively