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Thermal Analysis Techniques
A group of techniques in which a physical property
is measured as a function of temperature.
The sample is subjected to a predefined heating or
Types of thermal analysis
TG (Thermo gravimetric) analysis:
DTA (Differential Thermal Analysis):
DSC (Differential Scanning Calorimetry):
Differential thermal analysis
Le-Chateliar studied clays & minerals by an
examination of temperature –time curves.
Later Robert Austen improved technique by
Definition: DTA is a technique in which the
temperature between sample & thermally inert
reference substance is continuously recorded as a
function of temperature /time.
In DTA both test sample & an inert reference material
(alumina) – controlled heating or cooling programming.
If zero temperature difference b/w sample & reference material
– sample does not undergo any chemical or physical change.
If any reaction takes place temperature difference (∆T) will
occur b/w sample & reference material .
Differential thermal analysis is a
technique in which the
temperature of the substance
under investigation is
compared with the
temperature of a
thermally inert material.
Differential Thermal Analysis
sample and reference cells (Al)
Pt/Rh or chromel/alumel thermocouples one for the
sample and one for the reference joined to
differential temperature controller
alumina block containing sample and reference cells
Differential Thermal Analysis
instruments can be used at very high temperatures
instruments are highly sensitive
flexibility in crucible volume/form
characteristic transition or reaction temperatures can be
uncertainty of heats of fusion, transition, or reaction
estimations is 20-50%
Applications of Differential thermal
detection of any minerals in a sample
Polymeric Materials: DTA useful for the characterization of
polymeric materials in the light of identification of thermo
physical , thermo chemical, thermo mechanical and thermo
elastic changes or transitions.
Measurement of Crystalline: measurement of the mass fraction
of crystalline material in semi crystalline polymers.
Analysis of Biological Materials: DTA curves are used to date
bone remains or to study archaeological materials.
Differential Scanning Calorimetry
M.J.O’Neill in 1962.
First Adiabatic differential scanning calorimeter
that could be used in Biochemistry was developed by
P.L.Privalov in 1964.
temperature of furnace or time to get a thermogram. This is the
basis of Differential Scanning Calorimetry (DSC).
The deviation observed above the base (zero) line is called
exothermic transition and below is called endothermic transition.
The area under the peak is directly proportional to the heat
evolved or absorbed by the reaction, and the height of the curve is
directly proportional to the rate of reaction.
Heat Flux DSC
•sample and reference are connected by a low-resistance heat
flow path Al or Pt pans placed on constantan disc
chromel®-constantan area thermocouples (differential heat flow)
chromel®-alumel thermocouples (sample temperature)
one block for both sample and reference cells
the temperature difference between the sample and reference is
converted to differential thermal power, dDq/dt, which is
supplied to the heaters to maintain the temperature of the sample
and reference at the program value
Power Compensation DSC
Al or Pt pans
Pt resistance thermocouples
separate sensors and heaters for the sample and reference
separate blocks for sample and reference cells
differential thermal power is supplied to the heaters to maintain
the temperature of the sample and reference at the program
Applications of DSC
Protien Stability and Folding
Liquid Biopharmaceutical Formulations
Rank order Binding
Antibody Domain Studies
Characterisation of Membranes,lipids,nucleiec acids & micellar
Assesment of the effects of structural change on a molecules
Measurement of Ultra-light molecular interactions
Assesment of biocomparability during manufracturing.
Applications of DSC
composition of polymers is determined.
Melting point and lass transition temp can be determined
This can show the polymer degradation by lowering the melting
point(Tm).Molecular weight(low grade –low melting point) can be
Thermal degradation and impurities
Oxidative Stability: stability & optimum storage conditions
Drug analysis: widely used in Pharmaceutical industry(defining
processing parameters) and polymer industry(curing process.).
General Chemical analysis: Freezing point depression can be
used as a purity analysis tool.
Instrumental methods of Chemical analysis-GURDEEP
R.CHATWAL ,pg-no;701 to 739.
Instrumental methods of chemical analysis-B.K.SHARMA,pgno;M-390 to 421.
Instrumental methods of Chemical analysis,H.KAUR.pg.no-919