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.