Gas Chromatography Detectors - Summary of Detector Criteria > Page 20
Summary of Detector Criteria
1. Dynamic Range – (RD) – The dynamic range of a detector is that concentration range over which it will give a concentration dependent output. The units are dimensionless.
2. The Response Index – (r) – The response index of detector is a measure of detector linearity and would be unity for a truly linear detector. In practice the value of (r) should lie between 0.98 and 1.02. If (r) is known, quantitative results can be corrected for any non linearity.
3. Linear Dynamic Range – (DL) – The linear dynamic range of a detector is that concentration range over which the detector response is linear within defined response index limits. It is also dimensionless and is important when the components of a mixture cover a wide concentration range.
4. Detector Response – (Rc) – The detector response can be defined as the detector output per unit change in concentration (e.g. volts/g/ml) or, as the detector output per unit change of physicalpropertybeingmeasured (e.g.fortheFID, volts/gram of carbon/sec). In conjunction with the detector noise level it allows the sensitivity or minimum detectable concentration to be measured.
5. Noise Level – (ND) – The noise level of a detector is taken as the maximum amplitude of the combined short and long term noise taken over a period of 10 minutes; it is usually measured in volts.