this presentation can be very useful for pharma students.The detailed study of Ir can be possible by reading it thoroughly.

1. PRESENTED BY:-
MADHUR ARORA

2. BRIEF ABOUT IR
 Infra–red (IR) spectroscopy is the study of the scattering,
reflection, absorption or transmission of IR radiation in the
spectral range 800 nm to 1 000 000 nm (0.8 to 1000 μm). The
relationship between wave number in cm−1 and wavelength
(λ) in μm is given by:
 Three sub–regions :
 12 500 to 4000 cm−1 (0.8 to 2.5 μm; near IR),
 4000 to 400 cm−1 (2.5 to 25 μm; mid IR),
 400 to 10 cm−1 (25 to 1000 μm; far IR).
V= 1/ λ × 104

3. FOURIER TRANSFORM (FTIR)
 Fourier transform defines a relationship between a signal in
time domain and its representation in frequency domain.
 Being a transform, no information is created or lost in the
process, so the original signal can be recovered from the
Fourier transform and vice versa.

4. Operation of FTIR Spectrometer:
 The overall path of the two light beams determines
the degree of constructive or destructive interference
upon reflection to the detector.
 The beam from the source is modulated by the
interferometer, directed to the sample measured at the
detector.

6. ATR (Attenuated Total Reflectance):
 Attenuated total reflectance (ATR) is a
sampling technique used in conjunction with
infrared spectroscopy which enables samples
to be examined directly in the solid, liquid or
gas state without further preparation.

7. Sample
One Reflection
Liquid sample
Multiple reflection
Principle: Total Internal Reflection

8. OPERATION OF ATR
 This technique is based upon the fact that reflected
radiation slightly penetrates the surface from which it is
reflected.
 Refractive index of the cell(ATR crystal) is greater than that
of the sample medium and the angle is greater than the
critical angle, the infrared light beam will suffer total
internal reflectance at the interface.

9.  Snell’s law is used for
calculate angle of refraction
 n 1 sin α = n 2 sin β
 n 1 & n 2 = refractive index of
1 st and 2nd medium
 β= angle at which the
radiation reflected
 If n 2 is less than n 1 , an
angle α exists for which β is
90º, i.e for which the
radiation is completely
reflected. That angle is the
critical angle θ c .
n 1 sin θ c = n 2 sin 90º
θc = sin -1 n 2 /n 1
Sample
One Reflection

10.  But the beam of Light travels short distance(less than 2
μ m) in to lower refracting index material(sample).
 This penetrating beam is called as an evanescent wave.
If medium absorbs some of the light the reemerging
beam will be attenuated, that is reduced in intensity,
so it is called as ATR.
 The interaction of evanescent wave with the sample
essentially provide an IR spectrum of sample.

11. Evanescent Waves
The evanescent waves
penetrate 1 to 4
micrometers into the
sample at each reflection
point. A portion of the
wave is absorbed by the
sample. The altered
(attenuated) beam from
each wave exits at the
opposite end of the crystal
and is directed to the
detector. The detector
records the attenuated
beam as an interferogram
signal, which generates an
infrared spectrum

12. Crystal Composition
 Crystals are typically made of:
 Zinc Selenide (ZnSe)
• Germanium (Ge)
• Zinc Sulfide (ZnS)
• Silicon (Si)
• Diamond
• AMTIR: Germanium, Arsenic, Selenium (GeAsSe)
R.I Transmission
(cm-1)
2.4 20,000-650
2.2 17,000-950
4.0 5500-850

13. ADVANTAGES
• When an ATR accessory is used, most samples can be
run “neat”, which means “in their natural state”
• ATR sampling is fast and easy because little or no
sample preparation is required
• Other techniques, such as infrared transmission, often
require the sample to be heated, pressed or ground in
order to collect the spectrum

15. APPLICATIONS
• Solid analysis
• ATR is an excellent technique for measuring the
composition of solids
• Some examples of solids are films, fabrics, paper, hard
polymer sheets, glass, rubber
• ATR is an ideal technique for measuring dark colored
materials which often absorb too much energy to be
measured by IR transmission

16. • Liquid Analysis
• ATR can be used to analyze non-aqueous solutions
such a lubricants, oils, paints, glues, solvents, inks and
dyes
• Gels and pastes can also be analyzed.
• Used identification of paints, varnish.
• Powder Analysis
• Powders are easier to run by ATR than by IR
transmission, because little or no preparation is
required

17. CONCLUSION
• This category includes pure samples and mixtures that
are available in powdered from
• Some examples of pure samples and mixtures are
pharmaceuticals and pigments
Direct FT-IR of -
Solids
Solution FT-IR
Films
Biological membranes

18. Cosmic Gamma X UV IR Micro UHF
Short
Medium
Long
Ultra violet Infrared
Near Mid Far
190 400 800 2500 16000 25000 nm
Radio
Vis

19. BRIEF ON NIR
 The near–infrared (NIR) region of the electromagnetic
spectrum extends from about 780 to 2500 nm (or
12800 to 4000 cm–1).
 Its discovery by Herschel in 1800 was the first
indication that radiation, apart from visible radiation,
existed.
 The region is sub–divided into two regions: 780 to
1100 nm and 1100 to 2500 nm, the first of which is
named the Herschel region.

20. CHALLENGES OBJECTIVE
 For the qualitative
analysis of solid samples,
invariably NIR spectra
are often complex with
many overlapping peaks.
 NIR spectra are much
more difficult to
interpret than mid-IR
spectra
 Its strength lies in its
ability to identify
relatively pure samples
rapidly or to identify a
matrix of nearly fixed
composition, such as
tablets.

21. ADVANTAGE
 A further advantage of NIR spectra is that they
contain information about the physical properties
of the sample, such as particle size, compaction
density, polymorphs, etc., which often makes it
possible to differentiate between samples of the
same chemical identity, but of different grades or
from different sources.

22. OPERATION OF NIR
 NIR spectra may be measured by either reflectance, R,
or transmission, T.
 R = Ir/Io.
 T = It/Io.
 Reflected radiation is made up of two main
components – Specular and Diffuse radiation.
 Specular reflection is radiation that is simply reflected
directly from the surface of the sample and contains
little useful information about the sample for
identification purposes.

23. Principle: Diffuse Reflectance
Solid
sample
Diffuse reflection refers to
radiation that has penetrated
into the particles of the
sample, undergone multiple
reflections within the
substance and re–emerged
after the various characteristic
absorptions of the substance
have occurred.

24. Diffuse reflections give rise to chemical
information. The path length of the radiation is
dependent on numerous factors, such as particle
size, particle shape and sample compaction, and
therefore also contains information about the
physical state of the sample.
KUBELKA-MUNK FUNCTION
f(R) = 1-R2/2R = K/S
The KUBELKA–MUNK theory is a useful
approximation for NIR reflectance
measurements.
Reflection R = I/Io
Scattering coefficient S
Absorption coefficient = K

25. INSTRUMENTATION
Instrumentation for near-IR (NIR) spectroscopy is partially
similar to instruments for the visible and mid-IR ranges.
Source :- Quartz /halogen light, Light emitting diodes
Dispersive element :-Prism Diffraction grating
Interferometer(FT NIR)
Detector Silicon based ccds (in diode array instrument)

26. NIR Flex N-500

27. PHARMACEUTICAL APPLICATIONS
 NIRS are used for non-invasive measurement of the
amount and oxygen content of hemoglobin.
 Determination of particle size in USP grade Aspirin.
 Determination of blend uniformity.
 Determination of active ingredients in
multicomponent dosage forms.
 Determination of Polymorphs.
 Moisture determinations

28. OTHER APPLICATIONS
 Sensitive identity and quality
tests of liquid or solid actives
are performed directly in the
original shipping container.
 Virtually any liquid or
suspension can be analyzed
in both laboratory and at-
line situations.

29.  Automated transmission
or reflectance analysis of
layered, coated or cored
tablets, capsules, caplets,
geltabs and gelcaps

30. CONCLUSION
 Direct FT-NIR using probes of-
 Solids
 Solution FT-NIR
 Content uniformity
 Moisture determination in solids
NIR Radiations
Liquid
sample

31. REFERENCES
 Anthony C Moffat, M David Osselton, Clarke's
Analysis of Drugs and Poisons, by cengage
learning.
 Pavia, D.l, et al., spectroscopy by Brooks/Cole
 Current/Newer/Futuristic Trends in
Pharmaceutical Analysis.ppt by Dr. Saranjit
Singh
 http//www.autherstream.com