FOURIER TRANSFORM INFRA TED SPECTROSCPY - FTIR

1. Fourier Transform Infra Red
Spectroscopy
FT-IR

2. 1
KEY
ELEMENTS
Introduction
Principle
Instrumentation
Sample Preparation
Data Collection
Functional Group Identification
Applications
Advantages
Limitations
Conclusion
Quiz

3. Introduction To FT-IR Spectroscopy
2
FT-IR is an analytical technique used to identify organic and some
inorganic materials by determining the functional groups by the
application of IR radiation.
It could be applied for qualitative & quantitative analysis.
FT-IR spectroscopy is called a "fingerprint" technique because no
two different samples are known to give the same spectrum.
It can be used for solid, liquid, or gaseous samples, which give
spectra based on the vibrational transitions happening in the

4. Principle Of FT-IR Spectroscopy
3
Passing a beam of IR radiation through a sample, where some of
the radiation is absorbed by the sample while the rest is transmitted.
The transmitted radiation is then collected and analyzed by a
detector.
The resulting spectrum represents the amount of absorbed infrared
radiation at different wavelengths, providing information about the
types of chemical bonds present in the sample.
Unknown materials are identified by searching the IR spectrum
against a database that has a wide range of reference spectra.

5. 4
Instrumentation Of FT-IR Spectrometer
IR
Source
Sample
Compartme
nt
Interferomet
er
Detector
Interferogra
m
Comput
er
WAVE NUMBER
(Nm)
TRANSITTANCE
(%)
Database
Identificatio
n
R
S
IR BEAM

6. 5
IR Source:
 A broadband IR source.
 (Ex.: Globar - Nernst Glower - Halogen lamps).
Sample Compartment:
 Where the sample is placed for analysis.
 Includes a holder or cell appropriate for the sample type (solid, liquid,
or gas).
 Some sample compartments are temperature-controlled to allow
… Instrumentation Of FT-IR Spectrometer

7. 6
Interferometer:
 The core of FT-IR spectrometer is the interferometer, which modulates
IR beam.
 The most common type in interferometers is Michelson interferometer.
 The interferometer splits the IR beam into two paths, one for the
reference and one for the sample. The beams recombine, generating
an interferogram.
 Various mirrors and lenses are used to direct and focus the infrared
radiation onto the sample and into the interferometer.
… Instrumentation Of FT-IR Spectrometer

8. 7
Detector:
 Responsible for converting the IR radiation absorbed by the sample
into an electrical signal that can be analyzed and processed to
generate interferogram.
 Ex.: Mercury cadmium telluride (MCT) - Deuterated triglycine sulfate
(DTGS).
Computer:
 A computer controls the spectrometer and processes the interferogram
… Instrumentation Of FT-IR Spectrometer

9. 8
Sample preparation is a crucial step in FT-IR spectroscopy to
ensure accurate and reliable analysis of various sample types.
Proper handling & storage of sample is essential to avoid
contamination .
Regular cleaning of sample holders, windows, and accessories
helps maintain the integrity of the analysis.
Background spectra from the sample holder or reference material
may need to be subtracted from the sample spectrum to correct for
Sample Preparation For FT-IR

10. 9
… Sample Preparation For FT-IR

11. 10
… Sample Preparation For FT-IR
Solid Samples Preparation Techniques:
1. Direct Analysis:
 Some solid samples can be analyzed directly without any preparation.
 They are typically placed onto a sample holder, such as a diamond or
zinc selenide (Zn Se) window, and analyzed as-is.
2. KBr Pellet Method:
 Sample is ground with powdered (KBr) to form a homogenous
mixture.

12. 11
… Sample Preparation For FT-IR
… Solid Samples Preparation Techniques:
3. Mulling Technique:
 Sample is mixed with a non-reactive, IR-transparent liquid (Nujol)
forming a paste.
 This paste is spread onto an IR-transparent substrate as KBr window,
to form a mull.
 This method is useful for samples that are not soluble in common
solvents.

13. 12
… Sample Preparation For FT-IR
… Solid Samples Preparation Techniques:
5. Attenuated Total Reflectance (ATR):
 ATR accessories allow for the direct analysis of solid samples without
the need for extensive sample preparation.
 The sample is placed in contact with a crystal surface, and IR
radiation penetrates the sample, providing information about its
composition.
 This method is ideal for samples with surface-sensitive properties or
those that cannot be easily prepared as thin films or pellets.

14. 13
… Sample Preparation For FT-IR
Liquid Samples Preparation Techniques:
1. Thin Film Method:
 Sandwiching sample between two IR-transparent plates to create a
thin film.
 Suitable for samples that are soluble in volatile solvents or can form
stable films.
2. Evaporation Method:
 Evaporating sample in room temperature till dryness to form a thin

15. 14
… Sample Preparation For FT-IR
Gas Samples Preparation Techniques:
1. Gas Cell Method:
 Introduced sample into a sealed gas cell with IR-transparent windows.
 The cell is then placed in the sample compartment of the FT-IR
spectrometer.
 This method is suitable for analyzing gases or volatile compounds in
the gas phase.
2. Direct Analysis:

16. IR beam directed through the
sample which divided into two
paths, one interacts with the
sample, while the other serves
as a reference.
The two beams
recombine, resulting in
the interferogram
detected by the detector.
The interferogram is
Fourier-transformed to be
converted from the time
domain to the frequency
domain and the result is
an IR spectrum.
15
Data Collection In FT-IR
The IR spectrum is
displayed
graphically as a plot
of transmittance vs
frequency.
The processed
spectrum is stored
as a reference for
future analysis
Software
manipulates &
analyzes the
spectrum.

17. 16
There are several software available for controlling, processing,
and analyzing data obtained from FT-IR spectroscopy (Ex.: Omnic™
- Spectra Manager™).
Software choice depends on instrument compatibility & analysis
requirements.
Quality control measures, such as instrument calibration and
validation, are essential to ensure the accuracy and reliability of the
collected data.
… Data Collection In FT-IR

18. 17
Functional group identification in FT-IR spectroscopy is a
fundamental aspect for the determination of the chemical
composition and structure of compounds.
FT-IR spectra show absorption bands at specific frequencies due
to the vibration of chemical bonds within the molecule. corresponding
to specific functional groups present in the sample.
By comparing the positions and intensities of absorption bands in
the sample spectrum to reference spectra or literature data,
Functional Group Identification In FT-IR

19. 18
Each compound exhibits a unique
"fingerprint" of the spectrum, which
can be used for compound
identification and differentiation.
The following table shows the
functional groups identified by the
data collected from the FT-IR
spectrum of samples of Aerva
Lanata leaves.
… Functional Group Identification In FT-IR

20. 19
Applications Of FT-IR Spectroscopy

21. 20
Medical Researches: Identify biomolecules, such as lipids,
proteins, carbohydrates, and nucleic acids, within biological
specimens. Also can be used for disease diagnosis, tissue pathology,
and drug distribution studies.
Pharmaceutical Industry: In quality control to analyze drug
substances, formulations, and packaging materials, detect impurities,
assess drug stability, and ensure product quality and compliance with
regulatory standards.
… Applications Of FT-IR Spectroscopy

22. 21
Environmental Monitoring: In air quality monitoring, water quality
assessment, and soil analysis. It can detect pollutants, contaminants
& hazardous substances in environmental samples assessing their
impact on ecosystems.
Food & Agriculture: It can detect food adulteration, identify
nutritional components, assess food spoilage, and monitor
agricultural products for pesticides, toxins, and contaminants.
Forensic Sciences: Identifying trace evidence, analyzing fibers,
… Applications Of FT-IR Spectroscopy

23. Advantages Of FT-IR Spectroscopy
22
Supports quantitative analysis
providing accurate concentration
measurements.
Versatile and can analyze various
sample types, including solids,
liquids, gases
Rapid data acquisition compared to
dispersive IR spectroscopy
techniques.
Highly sensitive, can detect trace amounts of
analytes, (suites low concentrations or quantities
samples).
Covers a broad spectral range, allow
analysis of wide variety of functional
groups.
Non-destructive, allows analysis of samples without
altering chemical or physical properties, (so suites
valuable materials).

24. Limitations Of FT-IR Spectroscopy
23
Data interpretation can be a
challenge for complex samples with
overlapping bands.
Can’t detect atoms or
monoatomic ions as no
chemical bonds.
Can’t detect molecules
comprised of two identical
atoms such as N2 or O2.
Aqueous solutions are difficult to
be analyzed as water is a high IR
absorbent.

25. 24
FT-IR spectroscopy stands as a cornerstone technique in the realm
of analytical chemistry and material science. Its versatility, coupled
with its ability to provide detailed molecular information, renders it
indispensable across a broad spectrum of applications.
FT-IR spectroscopy offers more advantages, including high
sensitivity, wide spectral range, rapid data acquisition & versatility in
sample analysis. It facilitates qualitative and quantitative analysis of
diverse sample types, ranging from solids and liquids to gases,
without necessitating extensive sample preparation.
Conclusion

26. 25
Moreover, FT-IR spectroscopy enables the identification of
functional groups, structural elucidation, and characterization of
chemical compositions, aiding research and development efforts in
various industries.
However FT-IR spectroscopy limitations, it remains a fundamental
and indispensable tool for scientific research, quality control, and
problem-solving across disciplines, contributing to advancements in
fields such as pharmaceuticals, environmental and materials
sciences.
… Conclusion

27. Choose the correct answer:
1- In FT-IR spectroscopy, all of the following are sample
preparation techniques EXCEPT:
A. Pelletizing with KBr
B. Dissolving in water
C. Attenuated Total Reflectance (ATR)
D. Thin film deposition
2- Which of the following is a limitation of FT-IR
spectroscopy?
A. High sensitivity to water
B. Limited spectral range
C. Inability to analyze organic compounds
D. Low spatial resolution
3- Which of the following is NOT advantage of FT-IR
spectroscopy?
A. Rapid data acquisition.
B. Allows analysis of sample without altering its properties.
C. Can detect atoms or monoatomic ions. 26
4- FT-IR spectra show absorption bands at specific
frequencies due to chemical bonds:
A. Break down
B. Forming
C. Vibration
D. Converting
5- In FT-IR spectroscopy, the term "Fourier Transform"
refers to:
A. Conversion of time-domain data to frequency-domain data
B. Conversion of frequency-domain data to time-domain data
C. Amplification of signal strength
D. Manipulation of spectral peaks
6- In FT-IR spectrometer, the component splits the IR beam
is:
A. Detector
B. Monochromator
C. Sample compartment
QUIZ

28. True or False:
1- FT-IR stands for "Fast Transmission Infrared Spectroscopy.“
2- FT-IR spectroscopy can be applied for both qualitative and quantitative analysis of samples.
3- FT-IR spectroscopy is suitable for analyzing liquid & gas samples only without solids.
4- FT-IR spectroscopy can provide information about the presence of functional groups in a sample based on characteristic
absorption bands.
5- FT-IR spectroscopy is applied to detect pollutants & contaminants in environmental samples assessing their impact on
ecosystems.
6- Instrument calibration and validation are optional procedures in FT-IR spectroscopy.
7- The IR spectrum is displayed graphically as a plot of transmittance vs wavelength.
27
… QUIZ
Choose the correct answer:
7- What aspect can pose a challenge for data interpretation
in FT-IR spectroscopy when dealing with complex
samples?
A. Overlapping bands
B. High resolution
C. Low sensitivity
D. Baseline correction
8- One of sampling techniques of gases in FT-IR
spectroscopy is:
A. Thin film method
B. Condensation method
C. Gas cell method
D. Attenuated Total Reflectance (ATR)
Choose the correct answer True or false
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7
B A C C A D A C F T F T T F F

29. Hossam Khayyal
&
Naif Al-Wabran
BY
THANK YOU