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FTIR
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FACILITATORS:Dr. B.M. GurupadayyaProfessorDr. R.S. ChandanAsst. ProfessorDept. of pharmaceutical chemistry
JSS Universitycollege of pharmacyMysore
FOURIER TRANSFORM INFRARED
PRESENTED BY
Gritta Sebastian
Ist M.Pharm
Dept. of Pharmaceutics
JSS University
College of pharmacy
Mysore
TYPES OF IR INSTRUMENTS
IR instruments can be classified as:
1.Dispersive instruments
• Single beam IR spectrophotometer
• Double beam IR spectrophotometer
2.Non-Dispersive instruments
• Fourier transform infrared (FTIR) spectrometer
Fourier Transform Infrared (FT-IR) Spectroscopy is a modern tool to study the characteristics of molecules, either in solid, liquid or gas phase.
An FTIR spectrometer simultaneously collects spectral data in a wide spectral range.
The term Fourier transform infrared spectroscopy originates from the fact that a Fourier transform (a mathematical process) is required to convert the raw data into the actual spectrum.
FTIR spectroscopy is preferred over dispersive methods of infrared spectral analysis for several reasons:
It is a non-destructive technique
It provides a precise measurement method which requires no external calibration
It can increase speed, collecting a scan every second
It has greater optical throughput
It is mechanically simple with only one moving part
FTIR V
FTIR’s COMPONENTS
IR radiation source
Beam splitter
Fixed mirror
Moving mirror
Helium-Neon laser
Collimating mirrors
Sample holder
Detector
FTIR seminar
Interferometer
He-Ne gas laser
Fixed mirror
Movable mirror
Sample chamber
Light source
(ceramic)
Detector
(DLATGS)
Beam splitter
FT Optical System Diagram
The figure above shows what is referred to as the Michelson interferometer
Radiations from the source falls on the interferometer
It comprises of beam splitter, moving mirror, fixed mirror
The beam splitter splits the light into two half beams of equal intensities
One half of the beam is passed to the fixed mirror, Other half is directed towards the mirror
Light enters the spectrometer and is split by the beam splitter.
Speed of the moving mirror is controlled by
using a helium-neon laser beam
Because of the steady movement, detector receives constants signals of maxima & minima
Beams after undergoes reflection from the respective mirrors are recombined & send signal to the detector
Combined signal is called as interferogram
After that the interferogram is either transmitted or reflected to the sample cell
Samples absorbs only those IR frequencies which cause vibration within the sample molecules
The signal is transmitted to the detector where it gets measured
The coded signal were decoded by using computer Technique is called as Fourier Transformation
ADVANTAGES
Filtration of radiation from the source is not required
The data can be stored and reanalyzed
Enhanced frequency reproducibility
Enhanced frequency resolution
Less time consuming
DISADVANTAGES
Expensive
Required precision for mirror movement
Detection of the sample is influenced by water vapour, path length & chemical interference
APPLICATIONS
Opaque or cloudy samples
Trace analysis of raw materials or finished products
Kinetics reactions on the microsecond time-scale
Analysis of chromatographic and thermogravimetric sample fractions
REFERENCES Instrumental methods of chemical analysis; Gurdeep R. Chatwal;
Page no: 2.41-2.53
Pharmaceutical analysisO.V.K.ReddyPage no:1.681.72
Introduction to FTIR Spectrometry : www.thermonicolet.com Principles of instrumental analysis;
2nd editionDougles skoog & Donald .M.WestPage no:210-219