Frank Davis

Within this work it is our intention to provide an overview of the use of arrays or microelectrodes in the characterisation of environmental samples. Electrochemical methods are often a relatively simple and inexpensive alternative to spectroscopic or chromatographic methods for the analysis of a wide range of analytes. Arrays of microelectrodes display a number of advantages over simple planar macroelectrodes and the reasons for this will be detailed within this work. We will also describe some of the most common methods for constructing microarrays. The application of these arrays for analysis of environmental samples such as soil and water for heavy metal contamination has been the major focus of research in this field and comprises much of this review. However other systems will also be detailed such as determination of various anions or other samples such as pesticides.

We describe the development, validation and optimisation of label‐free immunosensors for Nerve Growth Factor (NGF) protein. Screen‐printed carbon electrodes were electrochemically coated with polyaniline, and onto this antibodies to NGF were immobilised using electrostatic or neutravidin‐biotin interactions. These were constructed manually or using an automated liquid dispensing system. QCM demonstrated deposition of individual layer stages and binding of NGF. Studies revealed clear increases in immunosensor impedance following antigen exposure. Automated methodologies produced sensors with lowered sample‐to‐sample variation. Affinity produced electrodes offered higher sensitivities than those produced utilising electrostatic interactions. NGF between 25–1000 pg mL⁻¹ could be determined using the optimised sensor.

A study into the ultrasonic initiated alkaline hydrolysis of triglycerides (also known as the saponification reaction) is described. Sunflower oil is used as a source of triglycerides. The reaction is driven by the ultrasound from either an ultrasonic water bath (35 kHz–85 W) or a probe (40 kHz–50 W) in the presence of potassium hydroxide (KOH). It will be shown that ultrasound is effective as a power source to initiate and drive the reaction, that a high reaction yield is achievable in only 15 min of total power application while working at ambient temperature, and that no detectable by‐products are generated during the reaction. Comparison of the two methods shows the ultrasonic probe to be the superior technique. Our method demonstrates reasonable yields can be obtained without the need for excess alkali or phase transfer catalysis. Curing the soap for several weeks allowed the saponification reaction to proceed to completion. Suggestions for a practical application have also been given.