Fluorescence detector:

This is similar to the design of fluorometers and spectrofluorometers where a photoelectric detector is located at 90o to the excitation beam. The easiest detectors use a mercury excitation source and one or more filters to isolate a band of emitted radiation. Many sophisticated instruments are based upon a xenon source and employ a grating monochromator to isolate the fluorescent radiation. These have the advantage of being highly sensitive, typically greater by more than an order of magnitude than most spectrophotometers and selective (specific) in picking out a specific component of a mixture which fluoresces from a host of other components. These are typically in the range of 10^-9 to 10^-12 g/mL.  Quite often the number of fluorescent species can be enlarged by preliminary treatment of samples with fluorescent derivative forming reagents. Further developments are taking place based on tunable laser sources leading to enhanced sensitivity and selectivity.