Near Infrared Analysis Applications

Near Infrared (NIR) Absorption Analysis


Near infrared includes electromagnetic wavelength range between 1100 and 2500 nm.

The NIR absorbance of a material depends primarily on its chemical composition.

NIR instruments typically make measurements by shining NIR light on the sample and measuring the received light at several wavelenghts. At least one wavelength is absorbed by the material being measured, and the others are chosen as appropriate to give the best stability and accuracy.

Water is the most common NIR measurement. This is because water is an extremely strong NIR absorber at its two absorption wavelengths of 1,940 and 1,430 nm. Also, no other common material absorb strongly at the 1,940 nm wavelength, making it easy for NIR techniques to distinguish water from the other constituents of the sample. 




Some examples of measurement in liquid phase applications:

  • Water in Ethylene dichloride, Refrigerants, Glycols, Liquid halogens (Cl2, Br2), Alcohols, Organic acids, Amines, Mineral acids, Solvent recovery.
  • Sodium hydroxide in Caustic scrubbers.
  • Metaphenylene diamine in Dimethylacetamide.
  • Ethyl hexanol in Diisooctylphtalate.
  • Polymerized material in Polymerization reaction mixtures.
  • Acetic acid in Water
  • Dimethylacetamide in Water
  • Organic solvents in Solvent stripping.


Some examples of measurement in gas phase applications:

  • Water in Halogens (Cl2, Br2), Natural gas, Phosgene, Air, Inert gases, Vinyl chloride monomer.
  • Ammonia in Polymerization feedstock stream.
  • Methane, Ethane in reaction gas mixture.
  • Hydrogen cyanide in reaction gas stream.
  • Ethylene in flue gas stream.
  • CO, CO2 in flue gas stream.





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