Fluorogen: organic chemical that emit light of a longer wavelength(thus high energy) after absorbing light of a shorter wavelength(thus lower energy). Fluorescence occurs when the substance jumps to exciting state after absorbing light, and then emits energy and light of lower energy.

set-up(light path): light source -> light selector for exciting light -> sample -> light selector of emitted light -> photomultiplier(measure of emitted light) -> photometer -> recorder.

Therefore the present of fluorogen can be detected by the peak of amount of light emitted.

Advantages:

  1. It is very sensitive.
  2. There are two parameters to determine the presence of fluorogen, more accurate

Note: ordinary cuvettes should work for MCA, which excites at 380nm, since glass may be used if exciting wavelength >= 320nm

reference: John F. Robyt and Bernard J. White, Biochemical Techniques-Theory and Practice, p53