Applications of infrared spectroscopy

Infrared spectroscopy applications in science

1. APPLICATIONS OF INFRARED SPECTROSCOPY DONE BY: SHRUTHI K ( 18308019) SUBJECT : TECHNIQUES IN MICROBIOLOGY

2. INFRARED SPECTROSCOPY Infrared radiation is -10 14 to 10 11 Hz on the electromagnetic spectrum. The energy of infrared radiation corresponds to energy differences between different vibrational modes in molecules. Diatomic molecules do not exhibit infrared absorption. If right amount of frequency is absorbed, the molecule is excited and releases IR photon to come back to ground state. In graph of infrared, light transmittance on the vertical axis vs. frequency or wavelength on the horizontal axis.

3. APPLICATIONS- which and what ? 1. Identification of functional group and structure elucidation Group frequency region - 4000-1500 cm -1 Fingerprint region - 1500-400 cm -1 Each atom of the molecule is connected by bond and each bond requires different IR region so characteristic peaks are observed. This region of IR spectrum is called as finger print region of the molecule. It can be determined by characteristic peaks.

4. ADAPTED FROM SIGMA ALDRICH

5. 2. Identification of exchangeable Hydrogen: Many bands change frequency when deuterium is substituted for Hydrogen. In general functional group is responsible for a given band, thus by observing the shift, the groups in which exchange has occurred is identified. A delay in shift due to the exchange is detected. Also, the number of hydrogen bonds and the functional groups engaged in hydrogen bonding . Apart from this, small molecules like riboflavin and adenine are detected and A:U ratio can be detected in tRNA . It is also used in Studying the progress of the reaction .

6. ADAPTED FROM PHYSICAL BIOCHEMISTRY – DAVID FREIFELDER

7. 3. Identification of substances IR spectroscopy is used to establish whether a given sample of an organic substance is identical with another or not. This is because large number of absorption bands is observed in the IR spectra of organic molecules and the probability that any two compounds will produce identical spectra is almost zero. So if two compounds have identical IR spectra then both of them must be samples of the same substances.

8. 4. To track organic nano particles across the universe: Scientists at NASA released information about a family of complex, carbon-rich molecules that are abundant throughout the universe. Scientists believe more than 20 percent of the carbon in the universe is tied up to polycyclic aromatic hydrocarbons, or simply PAHs. Using the Ames-developed PAH Infrared Spectroscopic Database, scientists will now have access to data on hundreds more compounds and several powerful new tools –including an advanced web app and a dedicated astronomical software package – to map the distribution of this life-essential element and track its role across the universe .

9. 5. Protein quantification and determination: Polypeptides and proteins contains strong absorption bands (peptide bonds) -CONH grouping. Termed as amide bands. Nine amide bands observed - amide A, amide B and amides I-VII in order of decreasing frequency. Displacement coordinates: C = O stretching (in plane) C-N stretching (in plane) N-H stretching (in plane) OCN bending (in plane) CNH bending (in plane) Three out-of-plane: C-N torsion, C = O and N-H out-of-plane bending .

10. SOURCE: JENA LIBRARY OF MACROMOLECULES

11. APPLICATION- when and where? IRS is a powerful spectroscopy technique and can utilized for both quantitative and qualitative analysis. It is an appealing technology for the food industry because it is simple, rapid, non-destructive measurement of chemical and physical components. FTIR-Fourier Transform Infrared Spectroscopy. Main aim is to measure the amount of light absorbed by a sample at each wavelength. Can detect range of functional groups and is sensitive to change in molecular structure.

12. APPLICATIONS OF FTIR IN FOOD Infrared milk analyzer -To determine fat, protein, lactose content. Measurement of degree of unsaturation of fats and oils. Identification of flavor and aroma. Used to analyse and evaluate essential components from cinnamon barks. For packaging film - To identify structural changes occurred due to exfoliation. Identification of wheat varieties and Edible oils - FTIR-spectra of bacteria are specific to a given strain and show the spectral characteristics of cell components.

13. Attenuated Total Reflectance-FTIR. Applied for , 1.Sugar Analysis- Based on bands in 1250-900cm region. 2.Fruit containing product - Spectra for detection of adulteration in fruit jams and purees. 3.Sweet Condensed Milk(SCM) - spectra region above 1500 cm is dominated by water. 4.Fats and Oils - detection based up on peak height of absorption band of isolated trans bonds at 996cm.

14. APPLICATION IN FORENSICS Most of the evidence left at crime scene consists of organic compounds. It does not alter the evidence since very small amount of energy are applied. Used to identify forged of altered documents by shining beam IRS. Fibers of various kinds are often identified by this methods.

15. APPLICATION IN HOMELAND SECURITY Identification of materials used to make improvised explosives. Some these materials are not popular explosives like nitroglycerin. (impurities) But are toxic industrial materials(TIMs) and toxic industrial chemicals(TICs). Department of homeland security uses IRS technology to search TIMs and TICs.

16. OTHER APPLICATIONS Quantification of clinical parameters in body fluids Analysis of kidney stone, nails and facial fat Prediction of Azodicarbonamide in wheat flour. Quantifying the total phenolic content and total carotenoid content in blackberries. Diagnosis and monitoring of cancer and other diseases by analysing body fluids.

17. REFERENCES Infrared spectroscopy in forensic: definition and uses, Cheyenne O, California, United states www.pharmatutor.org www.tecrea.com Freifelder D, Physical Biochemistry: Applications to Biochemistry and Molecular biology, 1983, W.H Freeman Publications https://www.pharmatutor.org/pharma-analysis/ http://jenalib.leibniz-fli.de/ https://www.nasa.gov/