Analyte detection

Analyte detection - context
Detection techniques - purpose
Chromatography - detector system
Detectors ... ?
Coupling chromatography & detectors
     Flame ionization detector (FID)
           General description of FID
           Illustration of FID
           Detailled description of FID
     Electron Capture Detector (ECD)
           General description of ECD
           Illustration of ECD
           Detailled description of ECD
     Comparison FID and ECD
           Type of detector
     UV-visible absorption detector
           General description of UV-vis-AD
                 UV frequency range
                 Principles of light absorption
                       Jablonski scheme
                 Chromophores
           Illustration of the UV-vis-AD
           Detailed description of UV-vis-AD
     Fluorescence detector (FD)
           General description of FD
                 Fluorescent light
           Illustration of FD
           Detailled description of FD
     Mass spectrometric detection (MSD)
           Brief description of MSD
End of lesson


Terminology

General description of ECD

 

Operating principle:

Eluting analytes scavenge electrons emitted by a radioactive source in the detector; the resulting drop in electric current generates a signal.

sensitivity:

increasing electro-negativity of analyte (i.e., electron scavenging efficiency of the analyte)
 
  well suited to detect analytes that contain nitro-, carbonyl-, and halogen groups

 

detectable by ECD:

NOT suitable for detection by ECD:


advantages:

  • highly sensitive to halogenated compounds and other molecules containing electronegative moieties


disadvantages:

  • compared to FID, much narrower linear response range (i.e., two orders of magnitude in concentration)