Application FTIR in

Medicine and DentistryProf.Dr. Amer A. TaqaUniversity of Mosul, College of DentistryDBS. Department

• Infrared spectroscopy is widely used in industry as well as in research. It is a simple and reliable technique for measurement, quality control and dynamic measurement. It is also employed in forensic analysis in civil and criminal analysis.

• Some of the major applications of IR spectroscopy are as follows:

Identification of functional group and

structure elucidation• Entire IR region is divided into group frequency region

and fingerprint region. Range of group frequency is 4000-1500 cm-1 while that of finger print region is 1500-400 cm-1.

• In group frequency region, the peaks corresponding to different functional groups can be observed. According to corresponding peaks, functional group can be determined.

• 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.

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.

• IR spectra of two enatiomeric compound are identical. So IR spectroscopy fails to distinguish between enantiomers.

• For example, an IR spectrum of benzaldehyde is observed as follows.

• C-H stretching of aromatic ring- 3080 cm-1

• C-H stretching of aldehyde- 2860 cm-1 and 2775 cm-1

• C=O stretching of an aromatic aldehyde- 1700 cm-1

• C=C stretching of an aromatic ring- 1595 cm-1

• C-H bending- 745 cm-1 and 685 cm-1

• No other compound then benzaldehyde produces same IR spectra as shown above.

Studying the progress of the reaction

• Progress of chemical reaction can be determined by examining the small portion of the reaction mixture withdrawn from time to time. The rate of disappearance of a characteristic absorption band of the reactant group and/or the rate of appearance of the characteristic absorption band of the product group due to formation of product is observed.

Detection of impurities• IR spectrum of the test sample to be determined

is compared with the standard compound. If any additional peaks are observed in the IR spectrum, then it is due to impurities present in the compound.

Quantitative analysis• The quantity of the substance can be determined

either in pure form or as a mixture of two or more compounds. In this, characteristic peak corresponding to the drug substance is chosen and log I0/It of peaks for standard and test sample is compared. This is called base line technique to determine the quantity of the substance.

• Due to its sensitivity to the chemical information and strcture of the molecule, infrared spectroscopy can play an important role in new applications such as in

• the life-science field and not only in the traditional fields of physics and chemistry.

• Spectroscopic techniques are simple, reproducible, non-destructive without particular sample preparation. As a result, they provide information for the functional groups, bonds and molecular structure.

• In 1949 Blout, Mellors and Woernley in 1952 reported that infrared spectra of human and animal tissues could provide information on the molecular structure of tissues. These studies met with limited success due to non-developed instrumentation available and little knowledge of spectroscopic properties of biological molecules and the complexity of the

• samples.

• The rapid experimental and theoretical development took place in 1970s, where Fourier Transform interferometers interfaced to digital computers.

• According to a wide range of studies, it has been proved that FT-IR spectroscopy has been a significant clinical technique, which provides detailed information of the chemical components of the tissues (proteins, lipids, carbohydrates, DNA). By analyzing chemical and biochemical changes, specific spectral features are to be considered for a diagnostic evaluation.

Difference IR spectrum of two healthy

patients is very small

0

.2

.4

.6

.8

1

1.2

1.4 A

bsor

banc

e

1750 1700 1650 1600 1550 1500 1450 Wavenumber (cm-1)

difference

Spectral deviations between “healthy” and

“ill” patients, exhibiting different RIAR values

- .15

- .1

- .05

0

.05

.1

.15

.2

Arb

itrar

y

1700 1600 1500 1400 1300 1200 1100 1000 900

Wavenumber(cm-1)

1550 RIAR 720 RIAR

20 RIAR

- .15

- .1

- .05

0

.05

.1

.15

.2

1600 1500 1400 1300 1200 1100 1000 900

Distribution between different types of diseases of 820

“ill” patients measured by FTIR spectra of their skin

820 personsTotal

(5%)40 personsAllergy

(8%)67 personsDiabetes

(9%)74 personsLesions of nervous system

(10%)82 personsDiseases of gastrointestinal segments

(33%)270 personsCancerous diseases

(35%)287 personsDiseases of cardiovascular system

820 personsTotal

(5%)40 personsAllergy

(8%)67 personsDiabetes

(9%)74 personsLesions of nervous system

(10%)82 personsDiseases of gastrointestinal segments

(33%)270 personsCancerous diseases

(35%)287 personsDiseases of cardiovascular system

Comparison of human hair infrared spectra of a healthy

(lower trace, full line) and a breast cancer patient (upper

trace, dashed line)

1800 1700 1600 1500 1400 1300 1200 1100 1000 900

Wavenumber(cm-1)

Abs

orba

nce

0.5 A.U.

In pharmaceutical

In biological

In Dentistry

Infrared Spectroscopic Identication of Chosen Dental

Materials

and Natural Teeth

INFRARED SPECTROSCOPY: A TOOL FOR DETERMINATION OF

THE DEGREE OF CONVERSION IN DENTAL COMPOSITES

References• Ajaj 2013, 2:9

http://www.progressbiomaterials.com/content/2/1/9• Vasiliki Dritsa FT-IR Spectroscopy in Medicine,National

Technical University of Athens, NTUA • Greece• Luciene Gonçalves Palmeira MORAES1,, Renata

Sanches Ferreira ROCHA1,, Lívia Maluf MENEGAZZO1,,Eudes Borges de ARAÚJO2,, Keizo YUKIMITU2

• , João Carlos Silos MORAES3J Appl Oral Sci. 2008;16(2):145-9

• Michael C. Martin,Advanced Light Source Division

Thanks for your attention!