The Multi Wavelength Fluorescence Detector The multi wavelength fluorescence detector contains two monochromators, one to select the excitation wavelength and the second to select the fluorescence wavelength or produce a fluorescence spectrum A diagram of the multi wavelength fluorescence detector is shown in figure 38. Figure 38.  The Fluorescence Spectrometer Detector The detector comprises a fluorescent spectrometer fitted with suitable absorption cell that is sufficiently small so as not to degrade the resolution of an LC column. There are

The Fluorescence Detector The fluorescence detector is one of the most sensitive LC detectors and for this reason is often used for trace analysis. Unfortunately, although the detector is very sensitive, its response is only linear over a relatively limited concentration range. In fact, the response of the detector can only be assumed to be linear over a concentration range of two orders of magnitude. Unfortunately, the majority of substances do not naturally fluoresce which is a serious

The Single Wavelength Excitation Fluorescence Detector The single wavelength excitation fluorescence detector is probably the most sensitive LC detector that is available, but is achieved by forfeiting versatility. A diagram of a simple form of the fluorescence detector is shown in figure 36. The excitation light is normally provided by a low pressure mercury lamp which is comparatively inexpensive and provides relatively high intensity UV light at 253.7 nm. Many substances that fluoresce will be excited by light of this

The Fluorescence Detector When light is emitted by molecules that are excited by electromagnetic radiation, the phenomenon is termed photoluminescence. If the release of electro-magnetic energy is immediate, or stops on the removal of the excitation radiation, the substance is said to be fluorescent. If, however, the release of energy is delayed, or persists after the removal of the exciting radiation, then the substance is said to be phosphorescent. Fluorescence has been shown to be extremely

the development of the separation. This gives directly the spectrum of the solute (i.e. a curve relating adsorption and wavelength). It should be understood, however, that to prevent condensation and a consequent build up of sample in the sensor cell, the cell and all conduits to and from the sensor cell must be maintained at a temperature at least 25ûC above the maximum temperature of the GC column oven. The problems of interfacing will be discussed in a subsequent chapter.   The Fluorescence Spectrometer   Fluorescence is a specific type of luminescence. When molecules are excited by electromagnetic radiation to produce luminescence, the phenomena is termed photoluminescence. If the release of electro-magnetic energy is immediate, or stops on the removal of the excitation radiation, the substance is said to be fluorescent. If, however, the release of energy is delayed, or persists after the removal of the exciting radiation, then the substance is said to be

9. Chrysene 10. Benzo(b)fluoranthene 11. Benzo(k)fluoranthene 12. Benzo(k)fluoranthene 13. Dibenz(a,h)anthracene 14.Indeno(1,2,3,cd)pyrene 15. Benzo(ghi)perylene Courtesy of the Perkin Elmer Corporation Figure 37. Separation of the Priority Pollutants Monitored by the Simple Fluorescence Detector There are some compromises between the expensive fluorescence spectrometer detector and the single wavelength excitation fluorescence detector. Some have a single monochromators that select the wavelength of the excitation light, others employ a single monochromator to select the emission wavelength or provide emission spectra