Analytical methods used for detection of physical property

ANALYTICAL METHODS USED FOR
DETECTION OF PHYSICAL PROPERTY
[ DSC & X-RAY DIFFRACTION ]
Presented By
SOVAN KAYAL
M.PHARM(1ST SEM)
NETAJI SUBHAS CHANDRA BOSE INSTITUTE OF PHARMACY

DIFFERENTIAL SCANNING CALORIMETRY [DSC]
Calorimeter- Heat flow in sample
Differential calorimeter- Heat flow in sample vs reference as function of time

DSC: The Technique
• Differential scanning calorimetry (DSC) measures the temperature and
heat flows associated with transitions in materials as a function of time
and temperature in a controlled atmosphere.
• These measurements provide quantitative and qualitative information
about physical and chemical changes that involve endothermic or
exothermic processes or changes in heat capacity.

Diagram of a DSC apparatus
 A DSC apparatus is built around
 A differential detector
 A signal amplifier
 A furnace
 A temperature controller
 A gas control device
 A data acquisition device

 DSC measures:
• Glass transitions
• Melting and boiling points
• Crystallization time and temperature
• Percent crystallinity
• Heats of fusion and reactions
• Specific heat capacity
• Oxidative/Thermal stability
• Reaction kinetics
• Purity

Modes and Principles of operation:

 Power Compensated DSC:
Temperature differences between the sample and reference are
‘Compensated’ for by varying the heat required to keep both pans at the
same temperature. The energy difference is plotted as a function of
sample temperature.

 Heat-flux DSC:
Heat flux DSC utilizes as a single furnace. Heat flow into both sample and
reference material via an electrically heated constantan thermoelectric disk
and is proportional to the difference in output of the two thermocouple
junctions.

 Operation Procedures:
Calibration of instrument
• Temperature, heat of reaction, heat capacity scale using high
purity standards (In, Sn, Bi, Pb, Au).
• Baseline correction for a given scan rate (1-40 K/min).
• Weight samples before (and maybe after) experiment.

 Advantages:
• Rapidity of the determination
• Small sample masses
• Versatility
• Simplicity
• Applicable
• Study many types of chemical reactions

 Disadvantages:
• Relative low accuracy and precision (5-10%)
• Not be used for overlapping reactions
• Need calibration over the entire temperature for DTA

 X-RAY:
• An electromagnetive wave of high energy and very short wavelength
(between ultraviolet light and gamma rays), which is able to pass
through many materials opaque to light.
Energy: 100eV to 100KeV
Wavelength: 0.01 to 10 nanometer.

 DIFFRACTION:
• The process by which a beam of light or other system of waves are
spread out as a result of passing through a narrow aperture or across an
edge, typically accompanied by interference between the wave forms
produced.

 X-RAY DIFFRACTION:
• A technique used to determine the atomic and molecular structure of a
crystal, in which the crystalline atoms cause a beam of incident X-rays
to diffract into many specific directions.
• The atomic planes of a crystal cause an incident beam of X-rays to
interfere with one another as they leave the crystal. The phenomenon
is called X-ray diffraction.
• A stream of X-rays directed at a crystal diffract and scatter as they
encounter atoms. The scattered rays interfere with each other and
produce spots of different intensities that can be recorded on film.

 HOW DIFFRACTION WORKS: SCHEMATIC

 FACTORS THAT AFFECT XRD DATA:
Sample not powdered fine enough.
May not give all d-spacing data (not random enough).
Analysis too fast (degree/minutes).
May not give accurate peak data.
Mixture of minerals.

 APPLICATION OF X-RAY DIFFRACTION:
Find structure to determine function of proteins.
Distinguish between different crystal structures with identical
compositions.
Study crystal deformation and stress properties.
Study of rapid Biological and Chemical processes.
Crystallographic applications.

 X-RAY DIFFRACTION IS IMPORTANT FOR:
Solid-state physics
Biophysics
Medical physics
Chemistry and Biochemistry

Analytical methods used for detection of physical property

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