DIFFERENTIAL THERMAL ANALYSIS AND DIFFERENTIAL SCANING COLORIMETRY
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This document discusses differential scanning calorimetry (DSC), a thermal analysis technique where the temperature and heat flow of a sample are measured as it is subjected to a controlled temperature program. DSC provides quantitative and qualitative data on physical and chemical changes that involve endothermic or exothermic processes, such as phase transitions, melting points, heat capacity, and oxidation. The document outlines the components of a DSC instrument and how it works, as well as applications of DSC in various fields including polymers, pharmaceuticals, and biochemistry.
DIFFERENTIAL THERMAL ANALYSIS AND DIFFERENTIAL SCANING COLORIMETRY
- 1. Prepared By D . Mahendra Dept of PA&QA
- 2. 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. TG (Thermo gravimetric) analysis: weight DTA (Differential Thermal Analysis): temperature DSC (Differential Scanning Calorimetry): temperature
- 4. 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. 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. sample holder sample and reference cells (Al) sensors one for thePt/Rh or chromel/alumel thermocouples 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
- 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. 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. 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. 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.
- 14. •sample holder •sample and reference are connected by a low-resistance heat flow path Al or Pt pans placed on constantandisc •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
- 16. 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 T = 0 inertgas vacuum inertgas vacuum individual heaters controller P reference pan thermocouple
- 17. 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. 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