Thermal Performance Variables and Electronic Considerations

Gas chromatographic columns are installed in a column oven in which the temperature must be controlled accurately and precisely, because column temperature has a pronounced influence on retention time. Any fluctuation in column temperature will yield an impact on the measurement of retention data and retention indices. Present oven geometries and electronic temperature control components are capable of thermostatting a column oven to zhO.TC. 

Columns for Gas Chromatography Performance and Selection, by Eugene F. Barry and Robert L. Grob Copyright 2007 John Wiley Sons, Inc. 

In modern gas chromatographs the temperature controller of a column oven is a microprocessor incorporated into a feedback loop, allowing both temperatureprogramming ramp profiles and isothermal heating to be accomplished accurately and reproducibly. Under microprocessor control, a flap or door movement permits blending the proper amount of ambient lab air with oven air in the control of oven temperature. In addition, a cryogenic value can be opened by a microprocessor for delivery of carbon dioxide or liquid nitrogen in the column oven. 

2 ADVANTAGES OF TEMPERATURE PROGRAMMING OVER ISOTHERMAL OPERATION 

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