In practice, no detector has a truly linear response (despite manufacturers claims) but most detectors will have a response approaching that of linear. It is difficult to apply a standard to detector linearity, but the Response Index (1) does help comparisons to be made between one detector with that of another.
Providing the response of the detector approaches linearity then its response can be described by the following simple equation,
y = Acr
where (r) is the response index and the other symbols have the
For a truly linear detector, r=1, and the extent to which (r) deviates from unity would be a measure of its non linearity.
Curves relating the detector output to different solute concentrations passing though it for different response values are show in figure 2.
Figure 2 Curves Relating Detector Output to Solute Concentration for Different Response Indices.
