Richard John

The use of microelectrodes to probe the electropolymerization mechanism of heterocyclic conducting polymers

Abstract Cyclic voltammetry and potential step experiments were used to investigate the electropolymerization mechanism of pyrrole at platinum micro- and macroelectrodes. The enhanced mass transport properties of microelectrodes have been used to probe certain aspects of the mechanism, particularly with respect to the formation of soluble intermediates during polymer growth. It was found that polypyrrole growth was largely the result of the continual precipitation of oligomeric intermediates from solution rather than the sequential addition of pyrrole monomers to the polymer chain ends of the deposited polymer.

Development of a polypyrrole-based human serum albumin sensor

Abstract An electrosynthetic method which is suitable for direct incorporation of antibodies into conducing polymeric coatings has been developed. The voltammetric behaviour of an anti-human serum albumin (anti-HSA) containing electrode has been considered. In the presence of HSA a response which may be analytically useful has been identified.

Doping-dedoping of polypyrrole: a study using current-measuring and resistance-measuring techniques

Abstract Two techniques, namely cyclic voltammetry with microelectrodes, and cyclic resistometry, have been used to investigate the nature of the doping-dedoping processes occurring at polypyrrole. Both studies confirm that the cation plays a significant role in these processes. The use of microelectrodes with cyclic voltammetry enables distinct cation responses to be observed, while the use of resistometry shows the effect of the cation in determining the polymer resistance at negative potentials.

The use of microelectrodes as substrates for chemically modified sensors: A comparison with conventionally sized electrodes

Abstract The electrosynthesis of conducting polymers on microelectrodes has been investigated in this work. It has been shown that the incorporation of reagents suitable for analytical purposes is more readily achieved on microelectrodes than on macroelectrodes. Advantages in the analysis procedures employed using modified microelectrodes were also observed. Electrosynthesis without deliberate addition of supporting electrolyte has been demonstrated and the use of these electrodes for analysis without supporting electrolyte has also been considered.

Dispersed mercury microelectrodes using non-conducting polymer coatings

Abstract The preparation and use of polymeric dispersed mercury electrodes were investigated. Both micro- and macroelectrodes were considered and it was found that the polymer-coated electrodes have greater chemical and mechanical stability than conventional mercury thin-film electrodes. It was also found that the polymeric microelectrodes display several advantages in performance over the macroelectrode counterpart.

Differential pulse voltammetric study of a typical anaerobic adhesive formulation coated on a glassy carbon electrode

Abstract The determination of copper (II) and iron (III) added to an anaerobic adhesive formulation was investigated by differential pulse voltammetry after application of a solution of the adhesive in acetone to a glassy carbon electrode. The best supporting electrolyte was 0.1 M sodium dodecyl sulphate, which ensured adequate surface contact with the adhesive coating. Under optimum conditions, copper (II) (as CuEDTA 2− ) could be determined at levels down to 0.1 mg l −1 and iron (III) (in some complexed form) down to 2.0 mg l −1 . The method is also capable of detecting the presence of poly (ethylene glycol) dimethacrylate, cumene hydroperoxide and N , N -dimethyl- p -toluidine in a typical formulation.

Direct Electrochemical Immunoassays Involving Adsorbed or Immobilised Species

Since the early 1970’s there has been much interest shown in the development of non-isotopic immunoassays. The main reasons for this stem from the perceived dangers of using radio-labelled substances (as required in radioimmunoassay), and the search for more selective, sensitive and precise methods of analysis. Much work has therefore been devoted to the development of fluorescent and enzyme-linked immunoassays, but it is only in recent years that there has been strong interest in the application of electrochemical techniques in this regard.1,2