ELECTROANALYTICAL STUDY OF XANTHOPHYLL AND ITS APPLICATION

The electroanalytical behaviour of xanthophyll was studied by differential pulse polarography and cyclic voltammetry.The reduction wave of xanthophyll at -0.92V(v.s.Ag/AgCl)in 1.25% tetrabutyl ammonium chloride solution(TBAC)was found for the first time.The optimum conditions for the determination of xanthophyll by DPP were established. The results from the application of cyclic voltammetry to study electrode process behaviour showed that the electrode reaction of xanthophyll at a hanging mercury electrode is quasi-reversible reaction.

ELECTROANALYTICAL CIIARACTERISTICS OF NICOTINIC ACID IN MICELLAR SOLUTION

The electroanalytical characteristies of nicotinic acid in miceilar solution,were studied by cyclic voltammetry,constant potential coulometry and chron ocoulometry.A procedure of the absorptive voltammetric determination of the drug was worked out.

Electroanalytical Investigation on Paracetamol on Boron-Doped Diamond Electrode by Voltammetry

An electroanalytical method was developed for the direct quantitative determination of paracetamol in tablets based on its oxidation behavior. The electrochemical oxidation and determination of paracetamol were easily carried out on born-doped diamond (BDD) electrode using two voltammetric techniques (CV and DPV). The electrochemical measurements performed by cyclic voltammetric (CV) and differential pulse voltammetry (DPV) techniques were carried out using a cathodically pretreated boron-doped diamond electrode in HClO4 and KClO4 electrolytes. HClO4 was then selected for analytical purposes and scan rate studies were also completed. The oxidation of the paracetamol is found to be irreversible and a diffusion-controlled nature of the paracetamol oxidation peak was established. A linear calibration curve for DPV analysis was constructed in the paracetamol concentration range from 0 μM to 13.87 μM, with 0.16 μM and 0.55 μM as the detection and quantification limit respectively.

Electrochemical reduction of Cr(Ⅵ)in the presence of sodium alginate and its application in water purification

Chromium(Cr)is used in many manufacturing processes,and its release into natural waters is a major environmental problem today.Low concentrations of Cr(Ⅵ)are toxic to human health and living organisms due to the carcinogenic and mutagenic nature of this mineral.This work examined the conversion of Cr(Ⅵ)to Cr(Ⅲ)via electrochemical reduction using gold electrode in an acidic sodium alginate(SA)solution and subsequent removal of the produced Cr(Ⅲ)-SA by the polymer-enhanced ultrafiltration(PEUF)technique.A solution of SA in nitric acid was used both as an electrolytic medium during the voltammetric measurements and bulk electrolysis and as an extracting agent during the PEUF technique.The electroanalysis of Cr(Ⅵ)was performed by linear sweep voltammetry in the presence of acidic SA solution to study its voltammetric behavior as a function of the Cr(Ⅵ)concentration,pH,presence of Cr(Ⅲ),SA concentration and scan rate.In addition,the quantitative reduction of Cr(Ⅵ)to Cr(Ⅲ)was studied through the bulk electrolysis technique.The results showed efficient reduction with well-defined peaks at approximately 0.3 V vs.Ag/AgCl,using a gold working electrode.As the pH increased,the reduction signal strongly decreased until its disappearance.The optimum SA concentration was 10 mmol/L,and it was observed that the presence of Cr(Ⅲ)did not interfere in the Cr(Ⅵ)electroanalysis.Through the quantitative reduction by bulk electrolysis in the presence of acidic SA solution,it was possible to reduce all Cr(Ⅵ)to Cr(Ⅲ)followed by its removal via PEUF.

Enzyme-catalyzed deposition of polydopamine for amplifying the signal inhibition to a novel Prussian blue-nanocomposite and ultrasensitive electrochemical immunosensing

The uncontrollable synthesis of Prussian blue (PB) and its weak stability toward OH -are great challenges affecting its electrochemical biosensing application. Herein we utilize the unique properties of chitosan (CS) to realize the facile and controllable synthesis of a CS-PB nanocomposite and combine it with the urease-catalyzed deposition of polydopamine (PDA) for amplifying the electrochemical signal inhibition of PB to develop a novel immunosensing method for protein detection. The immunosensor was constructed on a CS-PB modified electrode, and a urease-functionalized silica nanoprobe was prepared for tracing its sandwich immunoassay toward the model analyte of carcinoembryonic antigen. Besides the electrochem- ical impedance effect of the quantitatively captured nanoprobes, their enzymatic reaction can release numerous OH -to destroy the PB crystals and also induce the PDA deposition onto the immunosensor. These caused drastic electrochemical signal inhibition to PB. Based on the above multi-signal amplification mechanism, the method exhibits a very low detection limit of 0.042 pg mL^(-1) along with a very wide linear range of six-order of magnitude. In addition, the CS-PB based immunosensor has excellent specificity, repeatability, stability and reliability. Thus this PB nanocomposite and the proposed electrochemical immunosensing method reveal a promising potential for future applications.