Topics - Sensitivity
Unfortunately, in chromatography, sensitivity
has a dichotomy of meaning that has resulted from early definitions of detector performance being changed over the years. Originally, sensitivity was considered to define how small a mass or concentration of a solute could be unambiguously identified by a detector. This concept of sensitivity still persists, although it has been replaced in some cases by minimum detectable mass (MDM)
or, alternatively, minimum detectable concentration (MDC)
. Sensitivity, MDM or MDC are classically defined as the mass or concentration of solute passing through the detector that will give a signal equivalent to twice that of the noise. Originally the signal given by a detector for unit mass or unit concentration change was termed the detector response
. However, in modern terminology, the term ‘response’ is often replaced by ‘sensitivity’ which introduces even more confusion. It follows, therefore, when using the terms ‘sensitivity’ or ‘response’, their precise meaning must be clearly defined.