Principles and Practice of Chromatography - The Basic Column Chromatograph > The Detector Output > Page 59

Figure 27 Measurement of Detector Noise


Detector sensitivity or minimum detectable concentration (MDC) is defined as the minimum concentration of solute passing through the detector that can be unambiguously discriminated from noise, conventionally taken when the signal to noise ratio is two and this criteria has been adopted for defining detector sensitivity.

Thus for a concentration sensitive detector, the detector sensitivity (XD) is given by

The two important ranges that are specified for a detector are the dynamic range and the linear dynamic range. The dynamic range (DR) extends from the minimum detectable concentration (i.e. the sensitivity) to that concentration at which the detector no longer responds to any increase. The dynamic range is not usually pertinent to general analytical work but is important in preparative chromatography. The linear dynamic range or detector linearity is as important as sensitivity for any detector that is to be used for quantitative analysis. It is defined as the concentration range over which the detector response is linearly related to the concentration of solute passing through it.