Liquid Chromatography Detectors - The UV Detectors > The UV Absorption Detectors > Page 38

                                                                            

                          or         ln (IT)  =  ln (Io)  -  kcl

 

where (Io) is the intensity of the light entering the cell,
(l) is the path length of the cell,
and (k) is the molar extinction coefficient of the solute for the specific wavelength of the UV light.

Differentiating,

                                            

The sensitivity of the detector, as measured by the transmitted light, will be directly proportional to the extinction coefficient (k) and the path length of the cell (l).  To increase the sensitivity of the system, (l) must be extended but there is a limit to which (l) can be increased as the cell volume and, in particular, the length of the cell must be restricted. This is necessary to minimize peak dispersion in the sensor and to avoid more than a small fraction of a peak existing in the cell at any one time This problem has already been discussed.