1. Differential thermal analysis
& differential scanning
calorigraphy
By wilwin edara
(I/II M.Pharm)
CHIPS

2. 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
cooling program.

3. Types of thermal analysis
 TG (Thermo gravimetric) analysis:
weight
 DTA (Differential Thermal Analysis):
temperature
 DSC (Differential Scanning Calorimetry):
temperature

4. Differential thermal analysis
Le-Chateliar studied clays & minerals by an
examination of temperature –time curves.
Later Robert Austen improved technique by
introducing thermocouples.
Definition: DTA is a technique in which the
temperature between sample & thermally inert
reference substance is continuously recorded as a
function of temperature /time.

5. 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 .

6. DTA Principle
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.

7. Differential Thermal Analysis
sample holder
sample and reference cells (Al)
sensors
Pt/Rh or chromel/alumel thermocouples one for the
sample and one for the reference joined to
differential temperature controller
furnace
alumina block containing sample and reference cells
temperature controller
controls
for
temperature
atmosphere
Recording system
program
and
furnace

8. DTA Instrument

9. Differential Thermal Analysis
advantages:
instruments can be used at very high temperatures
instruments are highly sensitive
flexibility in crucible volume/form
characteristic transition or reaction temperatures can be
accurately determined
disadvantages:
uncertainty of heats of fusion, transition, or reaction
estimations is 20-50%

10. Applications of Differential thermal
analysis
Qualitative
and
Quantitative
Identification
of
Minerals:
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.

11. Differential Scanning Calorimetry
this
technique
is
developed
by
E.S.Watson
and
M.J.O’Neill in 1962.
 introduced
Conference
on
commercially
analytical
at
the
Chemistry
Pittsburgh
and
Applied
Spectroscopy.
First Adiabatic differential scanning calorimeter
that could be used in Biochemistry was developed by
P.L.Privalov in 1964.

12. Principle
In
DSC
the
heat
flow
is
measured
and
plotted
against
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.

13. DSC Curve

14. Heat Flux DSC
•sample holder
•sample and reference are connected by a low-resistance heat
flow path Al or Pt pans placed on constantan disc
•sensors
chromel®-constantan area thermocouples (differential heat flow)
chromel®-alumel thermocouples (sample temperature)
•furnace
one block for both sample and reference cells
•temperature controller
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

15. Heat flux DSC

16. Power Compensation DSC
individual
heaters
sample holder
Al or Pt pans
sample
pan
controller
P
reference
pan
inert gas
sensors
vacuum
thermocouple
T=0
Pt resistance thermocouples
separate sensors and heaters for the sample and reference
inert gas
vacuum
furnace
separate blocks for sample and reference cells
temperature controller
differential thermal power is supplied to the heaters to maintain
the temperature of the sample and reference at the program
value

17. Applications of DSC
Protien Stability and Folding
Liquid Biopharmaceutical Formulations
Process Development
Protien Engineering
Rank order Binding
Antibody Domain Studies
Characterisation of Membranes,lipids,nucleiec acids & micellar
systems
Assesment of the effects of structural change on a molecules
stabiity
Measurement of Ultra-light molecular interactions
Assesment of biocomparability during manufracturing.

18. Applications of DSC
Polymers:
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
determained.
Percentage Crytallinity
Thermal degradation and impurities

19. Liquid crystals
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.
Functional Applications:
Binding Studies

20. Of DSC
Binding Sites;

21. References:
 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
to 932.
 www.wikipidia.com
 www.microcal.com/technology/dsc.asp