A chromatography detector is a device used in gas chromatography (GC) or liquid chromatography (LC) to detect components of the mixture being eluted off the chromatography column. There are two general types of detectors: destructive and non-destructive. The destructive detectors perform continuous transformation of the column effluent (burning, evaporation or mixing with reagents) with subsequent measurement of some physical property of the resulting material (plasma, aerosol or reaction mixture). The non-destructive detectors are directly measuring some property of the column effluent (for example UV absorption) and thus affords for the further analyte recovery.
UV detectors, fixed or variable wavelength, which includes diode array detector (DAD or PDA). The UV absorption of the effluent is continuously measured at single or multiple wavelengths. These are by far most popular detectors for LC.
Fluorescence detector. Irradiates the effluent with a light of set wavelength and measure the fluorescence of the effluent at a single or multiple wavelength. Used only in LC
Electron capture detector, (ECD). The most sensitive detector known. Allows for the detection of organic molecules containing halogen, nitro groups etc.
Conductivity monitor. Continuously measures the conductivity of the effluent. Used only in LC when conductive eluents (water or alcohols) are used.
Photoionization detector, (PID). Measures the increase in conductivity achieved by ionizing the effluent gas with UV radiation.
Refractive index detector (RI or RID). Continuously measures the refractive index of the effluent. Used only in LC. The lowest sensitivity of all detectors. Useful when nothing else works and at high analyte concentrations.
Radio flow detector. Measures radioactivity of the effluent. This detector can be destructive if a scintillation cocktail is continuously added to the effluent.
Chiral detector. Continuously measures the optical angle of rotation of the elutant. Used only in LC when chiral compounds are being analyzed.