Gas chromatograph is a commonly used chromatographic product. In addition to quantitative and qualitative analysis, it can also determine the physical and chemical constants such as the partition coefficient, activity coefficient, molecular weight, and specific surface area of the sample on the stationary phase.
There are seven main types of detectors for gas chromatographs:
1. Hydrogen flame ionization detector (FID) is used for trace organic analysis.
2. The thermal conductivity detector (TCD) is used for constant and semi-micro analysis. Both organic and inorganic materials respond.
3, electron capture detector (ECD) for organochlorine pesticide residue analysis.
4. The flame photometric detector (FPD) is used for trace analysis of organic phosphorus and sulfides.
5, nitrogen phosphorus detector (NPD) for organic phosphorus, nitrogen compounds trace analysis.
6, catalytic combustion detector (CCD) for the analysis of flammable gases and compounds.
7. The photoionization detector (PID) is used for the trace analysis of toxic and harmful substances.
Classification of Chromatographic Detectors
1) According to the principle can be divided into optical detectors (such as ultraviolet, fluorescence, refractive index, evaporative light scattering), thermal detectors (such as adsorption heat), electrochemical detectors (such as polarography, Coulomb, Ampere), electrical detectors (Electrical Conductivity, Dielectric Constant, Piezoelectric Quartz Frequency), Radioactive Detector (Scintillation Count, Electron Capture, Helium Ionization), and Hydrogen Flame Ionization Detector.
2) According to the nature of measurement can be divided into general and exclusive (also known as selective). General-purpose detectors measure the properties of common materials, and they respond to both solvent and solute components, such as refractive index, evaporative light scattering detectors. General-purpose sensitivity is generally lower than that of proprietary models. The proprietary detector can only detect certain properties of certain components, such as ultraviolet and fluorescence detectors, and they only respond to components that have ultraviolet absorption or fluorescence emission.
3) According to the detection method is divided into concentration type and quality type. The response of the concentration detector is related to the concentration of components in the mobile phase, and the response of the mass detector is related to the amount of components passing through the detector in a unit time.
4) The detector can also be divided into two types that destroy the sample and do not destroy the sample.
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