Electrical principles of high-frequency gas volumetry
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Proper electrical calculation of a volumetric cell permits fruitful use of the possibilities of the high-frequency method of gas-volume analysis, especially when recording the evolution or absorption of gas during enzyme reactions. The selection of the optimal parameters of the cell permits achieving a sensitivity of ten-thousandths of a microgram. For instance, if a 1-mA current flows in the circuit of a 1-ml cell, the amplification factor of the electronic circuit is 50,000 and the indicator at the output of this circuit records a 5 μA change of current, the sensitivity of the gas-volumetric device, as is easily seen, is 0.0001 µl, which is an entire order of magnitude greater than the sensitivity of one of the most refined methods of gas-volume analysis, the “Descartes float” method.
The problem of the rational threshold of sensitivity, of course, can be solved only after analysis of the errors of the measuring apparatus, among which the error due to temperature instability plays an important role. Thermostatic control in this case (as in gasometric analysis performed by other methods) is the most efficient means of reducing the temperature errors.
KeywordsEnzyme Optimal Parameter Enzyme Reaction Current Flow Measuring Apparatus
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