Based On Dye Polymer Film Modified Electrodes And Determination Of Ascorbic Acid, Dopamine And Uric Acid

Ascorbic acid (AA) is a vital component in human diet and it is used for theprevention of scurvy and treatment of common cold, infertility and cancer. Dopamine(DA) is important neurotransmitter in our body, it is believed to be related to severaldiseases, such as Parkinsonism. Uric acid (UA) is another important compound in ourbody and its abnormal concentration levels will lead to several diseases such ashyperuricaemia and gout. AA, DA and UA usually coexist in our human body.Therefore, it is very important for diagnostic research to develop a sensitive andselective method for their selective or simultaneous determination. However, theoxidation potentials of AA, DA and UA are very close at bare electrodes. This make itdifficult for the simultaneous determination of AA, DA and UA.In recent years, to overcome these problems, various modified electrodes havebeen constructed and used to simultaneously determine AA, DA and UA. Polymers,carbon nauotubes and metal nanoparticles have garneded particular attention becauseof their respective advantages. But the unstability of the carbon nauotubes and metalnanoparticles modified electrodes and the poor sensitivity of the polymer modifiedelectrodes lead to the poor sensitivity for the simultaneous determination of AA, DAand UA.For sensitive and selective detection of AA, DA and UA. In this study, thecomposite film of the polymers combined with carbon nauotubes and metalnanoparticles are used to modify electrodes, the obtained composite film modifiedelectrodes not only exhibit good stability, but also improve sensitivity for thesimultaneous determination of AA, DA and UA.This paper includes three aspects as followed:1. A polycalconcarboxylic acid (CCA) modified glassy carbon electrode (GCE)was fabricated by electropolymerization and used to simultaneously determinedopamine (DA) and uric acid (UA). It was showed that the PCCA/GCE not onlyimproved the electrooxidation of DA and UA, but also resolved the overlappedoxidation wave into two well-defined and sharp oxidation peaks, corresponding to theoxidation of DA and UA, respectively. Under the optimal conditions, the anodic peak currents were correspondent linearly to the concentrations of DA and UA in the rangesfrom5.0-43.8μmol/L and5.0-50μmol/L, respectively. The correlation coefficientswere0.9998and0.9996. The detection limits were0.2μmol/L and0.5μmol/L for DAand UA. The proposed method had been used for the simultaneous determination ofDA and UA in their mixture with satisfactory results.2. A poly (acid chrome blue K)(PACBK) modified glassy carbon electrode(GCE) which had been pre-coated with carboxylic acid groups functionalizedmultiwalled carbon nanotubes (MWCNT)(PACBK-MWCNT/GCE) had beenfabricated and used for simultaneous detection of ascorbic acid (AA), dopamine (DA)and uric acid (UA). Scanning electron microscopy (SEM), cyclic voltammetry (CV),and differential pulse voltammetry (DPV) techniques had been used to characterizethe surface morphology and electrochemical characterization of thePACBK-MWCNT composite film. Due to the special characteristics of thenanostructured MWCNT and the PACBK film, the PACBK-MWCNT/GCE exhibitedhigh electrocatalytic activity, good selectivity and sensitivity for the simultaneousdetermination of AA, DA and UA in a phosphate buffer solution (PBS, pH4.0). Theseparations of anodic peak potentials of AA/DA, DA/UA and AA/UA at this modifiedelectrode were0.220V,0.136V,0.356V using DPV, respectively. Under theoptimum conditions, the calibration curves for AA, DA and UA were obtained in therange of30.0-500.0,1.0-60.0and1.0-75.0μmol/L, respectively. The detection limits(S/N=3) were10.0,0.3, and0.3μmol/L for AA, DA and UA, respectively. Due to thegood selectivety and sensitivity, the composite film modified electrode had beenapplied to the selective determination of DA in DA hydrochloride injections and AAand UA in urine samples with satisfactory results.3Cu nanoparticles (nano-Cu)-poly(sulfonazo III)(PSA) modified glassy carbonelectrode (nano-Cu-PSA III/GCE) was fabricated and then successfully used forsensitive simultaneous determination of ascorbic acid (AA), dopamine (DA) and uricacid (UA). The performance of the modified electrode had been characterized bycyclic voltammetry (CV). The behavior of nano-Cu-PSA III/GCE toward AA, DAand UA had been investigated by CV and differential pulse voltammetry (DPV). Themodified electrode showed excellent electrocatalytic activity toward theelectrooxidation of AA, DA and UA in a phosphate buffer solution (PBS, pH3.0).Linear calibration curves were obtained over the range of0.30-730,0.02-65and0.25-107μmol L1with detection limits of0.05,0.01and0.03μmol L1for AA, DA and UA (S/N=3), respectively. Moreover, the nano-Cu-PSA III/GCE surface exhibitshigh selectivity, good sensitivity and stability. The practical analytical utilities of themodified electrode were demonstrated by detecting the contents of AA and UA inurine samples and DA in human serum samples with satisfactory results.