thermal methods of analysis
TRANSCRIPT
THERMAL METHODS OF ANALYSIS
INTRODUCTION TO THERMAL METHODS OF
ANALYSIS &
THERMO-MICROSCOPY
SPEAKERS:RABIASUNDUS MUKHTAR
Thermal method of analysis:comprise a group of techniques in which a physical property of a substance is measured as a function of temperature while the substance is subjected to a controlled temperature programme.
Classification of thermo-analytical techniques:
Techniques most commonly used in pharmacy:
1. Thermo-microscopy 2. Differential thermal analysis
3. Differential scanning calorimetry 4. thermo-gravimetry
THERMO-MICROSCOPY:Developed by Austrian pharmacognosist Ludwig Kofler and his wife Adelheid Kofler and continued by Maria Kuhnert-Brandstätter.
This technique is also known as hot-stage microscopy.
Technique involves the observation of sample through a microscope fitted with a stage that can be heated or cooled at a controlled rate. Modern hot stages can cover the range of -180 to 600C.
DIFFERENTIAL THERMAL ANALYSIS
Speakers: Anam hassan Bushra khan
DEFINITION
Differential thermal analysis is the measurement of the difference in temperature between a sample and a reference as heat is applied to the system.
DTA GRAPH
FACTORS AFFECT RESULT IN DTA Sample weight Heating rate Particle size Atmospheric condition
INSTRUMENTATION
Apparatus for DTA consists of: Sample & reference holder A furnace A detector An amplifier A recorder
APPLICATIONS
Qualitative and quantitative identification of minerals.
Analysis of biological material To determine M.P, B.P, decomposition
temperature of organic compounds. Widely used for the quality control of a
large number of substances like cement, glass, soil etc.
Also used for the thermal stability of inorganic compounds and complexes.
DIFFERENTIAL SCANNING CALORIMETERy
SPEAKERS:HIRA ARSHADAMMARA FAROOQUI
TERMS TO KNOW:
CALORIMETER
DIFFERENTIAL CALORIMETER
DIFFERENTIAL SCANNING CALORIMETER Heat the sample with linear temperature ramp
PRINCIPLEThe measuring principle is to compare the rate of heat flow to the sample and to an inert material which are heated or cooled at the same rate.
DSC GRAPH
FACTORS AFFECTING DSC Sample shape
Carnoba Wax Polymer Blend
Polymorphism ofPhenobarbitol
Sample Size
Other Factors Furnace heating rate Sensitivity of recording mechanism Particle size Nature of sample Thermal conductivity
INSTRUMENTATION
TYPES OF DSC INSTRUMENTS
Power compensation DSC
Heat-flux DSC
Pt resistance thermocouples
Chromel-alumel thermocouples
Separate sensors & heaters for the sample & reference
Sample & reference are connected by a low-resistance heat flow path
separate blocks for sample and reference cells
one block for both sample & reference cells
APPLICATIONS Qualitative analysis
Quantitative analysis
Detection of impurities
Heat of fusion and extent of crystallinity can also be determined. To study and characterize polymers and their identification
Discriminate several commercial polymers in a mixture. Determine melting and boiling points more accurately Determine moisture content (moisture presence causes peaks regarding dehydration).
Use to study phase transition Decomposition of inorganic metals like alloy etc. Physical changes of excepients during storage of dosage form DSC with the support of X-ray diffraction and IR spectroscopy are used as screening technique for the compatibility testing of a drug with excepients.
THERMOGRAVIMETRY
SPEAKERS:
MADIHA AHMED
&
NOOR- UL- AIN
THERMOGRAVIMETRY“…. a technique in which the mass of a substance is measured as a function of temperature, while the substance is subjected to a controlled temperature programme.”
THERMOBALANCE DEVICE
PARTS OF THERMOBALANCE
3 Essential parts of thermo balance which are as follows:
Programmable Furnace
Microbalance
Recorder
PROGRAMMABLE FURNACE:
A furnace is an enclosed structure used for heating materials to very high temperatures.
MICROBALANCE
A microbalance is capable of making precise measurements of weight of objects of relatively small mass.
RECORDER:
Recorder is use to record the data in computer in graphical form for further interpretation.
TEMPERATURE PROGRAMMER
BALANCE
CONTROLLER
POWER FURNACE TEMP.
SAMPLE TEMP.
WEIGHTGAS IN
GAS-TIGHTENCLOSURE
SAMPLE
HEATER
INSTRUMENTATION:
TGA CURVE:
The plot also shows the derivative of the TG curve, or the DTG curve, which is often useful in revealing extra detail, such as the small event around 400°C.