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Infrared Spectroscopy, Gas Chromatography/Infrared in Food Analysis


  1. Ranjana Mehrotra

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a1013

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Mehrotra, R. 2006. Infrared Spectroscopy, Gas Chromatography/Infrared in Food Analysis. Encyclopedia of Analytical Chemistry. .

Author Information

  1. National Physical Laboratory, New Delhi, India

Publication History

  1. Published Online: 15 SEP 2006


Infrared (IR) radiation is usually defined as that electromagnetic radiation whose frequency is between 20 and 14 500 cm−1. Within this region of the electromagnetic spectrum, chemical compounds absorb IR radiation provided there is a dipole moment change during a normal molecular vibration, molecular rotation, and molecular rotation–vibration or from combinations, differences and overtones of the normal molecular vibrations. The frequencies and intensities of the IR bands exhibited by a chemical compound uniquely characterize the material and its IR spectrum can be used to identify and quantify a particular substance in an unknown sample. IR spectroscopy in both the mid-infrared (MIR) and near-infrared (NIR) regions is emerging as a qualitative as well as quantitative analytical technique with great potential in a wide range of applied areas. The prime advantage of IR spectroscopy in food applications is that once the instrument has been calibrated, several constituents in a sample can be measured rapidly and simultaneously. No sample manipulation is required. It is also applicable to on-line analysis in the food processing industries.