Electrodes biotechnological applications

The electrical conductivity detector is probably the second most commonly used in LC. By its nature, it can only detect those substances that ionize and, consequently, is used frequently in the analysis of inorganic acids, bases and salts. It has also found particular use in the detection of those ionic materials that are frequently required in environmental studies and in biotechnology applications. The detection system is the simplest of all the detectors and consists only of two electrodes situated in a suitable detector cell. An example of an electrical conductivity detector sensing cell is shown in figure 13. 

A critical factor for biotechnology application is the stability of the enzyme electrode. Hydrogenase immobilized into carbon filament material has high level of both operational and storage stability. Even after the half year of storage with periodical testing, the enzyme electrode preserved more than 50 % of its initial activity [9,10], Thus, it is possible to achieve appropriate stability of the enzyme electrode, suitable for hydrogen fuel cells development. 

Beside properties of inertness and stability, carbon electrodes have a wide potential range when compared to gold electrodes, which are more popularly used in electrochemical laboratories and fuel cells. The modification of the carbon surface is of importance in electrocatalytic, analytical, and biotechnological applications. 

Especially for medical and biotechnological applications miniaturized planar pH electrodes are needed. Here metal/metal oxide electrodes and electrodes based on ion-selective field effect... 

The determination of glucose is one of the most frequently perfomed routine analyses in clinical chemistry as well as in the microbiological and food industries. Here, the application of glucose electrodes appears to be the method of choice. Moreover, in combination with other enzymes, glucose oxidase sensors are applicable to the measurement of di- and polysaccharides and amylase and cellulase activity, which is required in many biotechnological processes. This versatility explains, why numerous researchers worldwide are concerned with the development and optimization of glucose sensors. 

Appropriate protective membrane covering the electrode or/and modification of the electrode surface permit the operation of voltammetric sensors independently of the solution variables. This feature plays a critical role especially in reactions occurring in suspensions, emulsions or in biofluids (cf. paragraph 7.3). The application of voltammetry and polarography is discussed in monographs such as [3] or [140]. The problems of electrochemical detection techniques in clinical, biotechnological and environmental applications for the biosciences are dealt with in [141]. 

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