Gas Chromatography Detectors - Temperature Sensitivity > Page 19
Detector temperature sensitivity varies greatly from one detector to another. The FID used in GC is virtually insensitive to temperature changes but this may not necessarily be true for the associated electronics. In contrast the katharometer detector is extremely sensitive to temperature changes (the reason for this will be clear when the katharometer detector is discussed) and must be thermostatted in a separate oven. Temperature changes together with changes in flow rate are the two main sources of drift in GC detectors.
The overall temperature sensitivity of the detector system (DT) is defined as the change in output in millivolts for one degree change in temperature (˚C). Some detectors have a limited temperature range over which they can operate satisfactorily and thus the maximum and minimum operating temperatures should also be available. The temperature sensitivity can be used to calculate the temperature change (NT) that would provide a signal equivalent to the detector noise (ND),
It is clear that a knowledge of (NT) can be used in the same way as (NP) and (NQ) in detector design