Thermal analysis techniques measure physical properties as a function of temperature. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) compare the temperature of a sample to an inert reference as each is subjected to a heating or cooling program. In DTA, any temperature difference between sample and reference indicates a chemical or physical change in the sample. DSC directly measures heat flow into or out of the sample, allowing determination of transition temperatures and heats of reactions. Both techniques find applications in chemistry, materials science, polymers, pharmaceuticals and more.

1. Differential thermal analysis
& differential scanning
calorigraphy
Prepared By :
Mahendra G S
M-Pharm,Pharmaceutical
Chemistry
JSSCP, MYSURU

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 program and furnace atmosphere
Recording system

8. DTA Instrument

9. 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 commercially at the Pittsburgh Conference on
analytical Chemistry 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
sample holder
Al or Pt pans
sensors
Pt resistance thermocouples
separate sensors and heaters for the sample and reference
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
sample
pan
DT = 0
inert gas
vacuum
inert gas
vacuum
individual
heaters
controller DP
reference
pan
thermocouple

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,pg-no;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