Font Size: a A A

Study On Amperometric Glucose Biosensor, Iodide Electrodes With High Selectivity And Solid-State PH Electrodes

Posted on:2004-05-08Degree:MasterType:Thesis
Country:ChinaCandidate:Q ZhaoFull Text:PDF
GTID:2168360092995150Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
This thesis consists of three parts. Each part includes a review and a research report.Since the work of Leland C. Clark, electrochemical biosensors have attracted a great deal of interest and have become the subject of intense investigations. The electrochemical biosensors perform simple, fast, specific and accurate monitoring with compact and user-friendly instrumentation to transform traditional methods of analysis. The first successful electrochemical biosensor is the amperometric glucose biosensor using the Clark-type oxygen electrode with direct electron transfer from the glucose oxidase to the surface of the electrode. However, there are some disadvantages in using the oxygen electrode-based glucose biosensor. It is insensitivity in view of slow process of direct electron transfer. Variable oxygen concentrations in the sample may introduce fluctuations into the electrode response. The glucose biosensor uses a relatively high potential, which is necessary in order to efficiently oxidize hydrogen peroxide. At this potential, ascorbic acid and uric acid always found in the blood sample are oxidized electrochemically and cause interfering signals in the amperometric measurements.Electron transfer mediators are involved to circumvent these disadvantages. The mediators include ferrocene and its derivatives, potassium hexacyanoferrate and tetrathiafulvalene. Water-soluble dyes such as methylene blue, neutral red, toluidine blue and methyl viologen have also been used as mediators in solution because of their high electron transfer efficiency and low cost. l-Nitroso-2-naphthol-6-sodium sulphonate ferric salt (naphthol green B) has excellent redox characteristics. In Part I of the thesis, the soluble dye, naphthol green B, was used as a new mediator to develop an amperometric glucose biosensor. Naphthol green B, which is low cost andeasy obtained, has been shown to be an efficient mediator, promoting electron transfer from glucose oxidase to graphite electrode. The naphthol green B has low formal potential, which can reduce the overvoltage of the H2O2 oxidation to eliminate electrochemical interference. Rapid response, oxygen independence and high sensitivity are shown by the naphthol green B mediated biosensor. Under the conditions of our studies, naphthol green B performs better than ferrocene and its derivatives in terms of electroactivity, especially the high sensitivity and low oxidation-reduction potential. Naphthol green B can be used successfully as a mediator for detecting glucose.Design, synthesis and application of highly selective neutral carriers are main research subjects in the ion selective electrode studies. Recently, study on solvent polymeric membrane (SPM) anion selective electrodes based on metal complexes as neutral carrier and exhibiting anti-Hofmeister selectivity pattern is an important project in the fields of electrochemistry and electroanalytical chemistry. Part II of the thesis focuses on the development of SPM anion selective electrodes based on new neutral carriers and their application as electrochemical sensors in food and medicine.New solvent polymeric membrane electrodes based on Schiff base complexes of [Mn(HI)-BSAPC] and [Mn(III)-BSAPDCA] are first described, which demonstrate excellent selectivity toward iodide ion. The resulting electrodes exhibit potentiometric anion-selectivity sequences deviated from the Hofmeister pattern. Bis(salicylaldehydearmnopropanol)chloromanganese(III) [Mn(III)-BSAPC], bis-(salicylaldehydeaminopropanol)nickel( II) [Ni( II )-BSAPC], bis(salicylaldehyde-aminopropanol)zinc( II) [Zn( II )-BSAPC], bis(salicylaldehydeaminopropanol)di-chloroaceticdimanganese(III) [Mn(III)-BSAPDCA] and bis(salicylaldehydeamino-propanol)dizinc(II) [Zn( II )-BSAPDCA] were synthesized for preparation of iodide ion selective electrodes. The electrodes incorporating Schiff base complexes of Manganese(III) have the advantages of low resistance, fast response, fair stability and reproducibility. The selectivity sequence is iodide ?perchlorate > salicylate > thio...
Keywords/Search Tags:biosensor, mediator, naphthol green B, iodide-selective electrode, neutral carrier, Schiff base complex, metal oxide electrode
PDF Full Text Request
Related items