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Catecholamine precursors and metabolites are emerging as a prominent biomarker for the prognosis and diagnosis of many pathological conditions. This article details the fabrication, features and efficacy of the voltammetric sensor based on copper nanoparticles (CuNP)-decorated poly-3-Amino-5-mercapto-1,2,4-triazole-modified glassy carbon electrode p(Cu-AMT/GCE) for the individual and simultaneous determination of L-Dopa and Vanillylmandelic acid (VMA). The modified electrode has been characterised via different analytical techniques. The CuNP-decorated polymeric film enabled the formation of well-defined and well-separated oxidation peaks for the analytes with a limit of detection 6.80 × 10–8 mol L−1 and 9.90 × 10–8 mol L−1, respectively, for L-Dopa and VMA. Scan rate studies reveal the involvement of a reversible two electron–two proton reaction for the electrooxidation of L-Dopa and an irreversible, one electron–one proton reaction for VMA on p(Cu-AMT/GCE). The credibility of the sensor was ascertained from reproducibility, repeatability and stability studies. The satisfactory results obtained from the interference studies and adequate recovery values achieved from spike recovery analysis in synthetic physiological fluids substantiate the practical applicability of the sensor. [ABSTRACT FROM AUTHOR]

The article details the development of a poly(para amino benzene sulfonic acid) modified glassy carbon electrode as a sensor for simultaneous determination of purine bases; guanine, adenine and uric acid. When 0.1 M NaOH was used as the supporting electrolyte the electro-oxidation of these analytes took place at well resolved electrode potentials which facilitated their simultaneous determination without any electrode fowling. The sensor response has been calibrated for both simultaneous and individual determination. Wide linear working concentration ranges and good detection limits were obtained for both. The selectivity of the sensor for simultaneous determination has been checked among these purine bases as well as in the presence of other possibly co-existing species. The sensor has been demonstrated to be efficient for determination of uric acid, guanine and adenine in acid denatured herring sperm DNA. The mechanistic and kinetic parameters such as charge transfer coefficient, number of electrons involved in the rate determining step, diffusion coefficient and heterogeneous rate constant for the electro-oxidation of these bases on the poly(para amino benzene sulfonic acid) modified glassy carbon electrode has also been determined. [ABSTRACT FROM AUTHOR]

This article details a voltammetric sensor for the simultaneous determination of norepinephrine (NE) and tyramine (TYM) using poly (L-arginine) and reduced graphene oxide composite film modified glassy carbon electrode (p (L-Arg)/ERGO/GCE). Under optimized conditions, the sensor displayed well separated and resolved peaks for the electro oxidation of NE and TYM. Quantification of these analytes were achieved with wide linear ranges and low detection limits both individually and simultaneously. The mechanistic parameters have been clearly addressed. The efficacy of the proposed sensor has been proved by the successful application of the method in physiological fluids. • A simple and facile voltammetric sensor based on p(L-arginine)/reduced graphene oxide composite film modified GCE. • Sensor displayed well separated and well resolved peaks for the electro oxidation of Norepinephrine and Tyramine. • Individual and simultaneous determination have been achieved with wide linear ranges and low detection limits. • Reliability of the proposed method has been certified in physiological fluids. [ABSTRACT FROM AUTHOR]