Use of the Enzyme Thermistor for Continuous Monitoring and Control in Biotechnology
The enzyme thermistor is a simple flow calorimeter designed for analysis of substances with the aid of immobilized enzymes Figure 1 schematically illustrates a recent version of this instrument in which a thermostated aluminum block providing constant temperature surrounds the small plastic column (0.2 – 1 ml) which contains the preparation of immobilized enzyme (1). The temperature at the outlet of the column is continuously measured with a thermistor with a maximal resolution of 10–5 deg. Short sample pulses yield temperature peaks proportional to concentration. If a sample is continuously introduced, the temperature reaches a steady state level again proportional to concentration. The measuring range lies within 1 to 10-6 mol/L. Enzymic reactions are generally highly exothermic, which makes the assay principle both general and specific. Furthermore, its insensitivity to the optical properties of such sample makes it specially valuable for analysis on crude solutions such as serum, urine, milk and fermentation broths. The insensitivity to disturbances is further increased by the use of an inert reference column in a split-flow differential system. The use of excess amounts of enzyme makes the system suitable for continuous analysis because of its high opeational stability.
KeywordsImmobilize Enzyme Continuous Monitoring Alginate Bead Voltage Control Oscillator Continuous Analysis
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