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Medicines design II - solid dosage forms > L6 Thermal Anal > Flashcards

L6 Thermal Anal Flashcards

0
Q

Thermal analysis methods measure

A

Heat exchange while heating or cooling a sample at a controlled rate

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1
Q

All physical changes are accompanied by…

A 
Heat exchange (deltaH)
Either to or from surroundings
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2
Q

Thermal analysis tools used to characterise… 7

A 
Melting point
Heat capacity
Kinetics of reaction
Kinetics of decomposition (shelf life)
Crystalline state of matter (polymorphism amorphous content,glass transitions, solvates/hydrates.
Purity and stability
Compatibility with excipients
J
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3
Q

Six thermal analysis techniques

A 
Thermomicroscopy
Thermogravimetric analysis (TGA)
Thermomechanical analysis (TMA)
Differential thermal anyalysis (DTA)
Differential scanning calorimetry (DSC)
Isothermal microcalorimetry (ITM)
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4
Q

TGA stands for

A

Thermogravimetric analysis

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5
Q

TGA measures…. As a function of….

A

Weight of a substance as a function of ramping temperature

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6
Q

TGA Requires…

A

Vacuum mass balance with sensitivity of 0.1microg

This instrument is hermetically sealed to allow atmospheric pressure to be controlled

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7
Q

TGA studies…and … of….

A

Stability and kinetics of drug decomposition

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8
Q

TGA curve measures

A

Mass over temp

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9
Q

Look at pictures of curves in book for TGA

A

.

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10
Q

Three components of TGA machine?

A

Microbalance, sample and furnace

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11
Q

Typical application of TGA…

A

Quantification of water loss

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12
Q

DTA stands for

A

Differential thermal analysis

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13
Q

DTA monitors….. and …. as….

A

Sample and reference as they are heated at a constant rate

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14
Q

DTA graph shows …. Against …. To obtain ….

A

Delta T against time

To obtain a thermogram

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15
Q

DTA provides…

A 
Follow endo (heat absorbed) or exothermic transitions during a chemical process.
Provides only qualitative or semiqualitative method mor measuring calorimic data.
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16
Q

Basic set up of DTA?

A

One heat source for sample and reference

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17
Q

Heat flux DTA

A

One heat source for sample and reference.

Heat converted to power.

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18
Q

Endothermic

A

Heat abosorbed.

Temp of sample is less than reference because it is taking in energy to fuel a reaction eg. Melting point transition.

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19
Q

Exothermic reaction

A

Heat evolved
Temperature of sample cell is higher than that of the reference becuase a sample is giving out energy as a product of a reaction.

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20
Q

Example of an exothermic reaction

A

Crystallisation

21
Q

Example of an endothermic reaction

A

Melting point transition

22
Q

DSC Stands for…

A

Differential scanning calorimetery

23
Q

how does DSC work?

A

Similar to DTA except erasure the amount of energy required to keep the sample at the same temperature as the reference.

24
Q

DSC is the preferred temperature ramping technique as….

A

Provides detailed info about physical and energetic properties of a substance.

25
Q

DSC provides qualitative or quantitative information

A

Quantitative

26
Q

DSC measures …, …. and ….

As a function of …. and …..

A

Endothermic, exothermic and heat capacity changes as a function of
Time and temperature.

27
Q

How does power decompendated DSC work?

A

DeltaT compensated for by varying heat to keep sample and ref at same temperature.
Using platinum heat sensors

28
Q

DSC is plotted as…

A

Energy provided plotted as function of temperature the sample and ref are being raised to

29
Q

DCS has single/separate furnaces

A

Separate

30
Q

Area of the dip in a power over temp graph for DSC is equal to…

A

Enthalpy

31
Q

When a sample reaches melting it…

A

Remains at that temperature until all the sample has passed into the liquid state.
Because if the endothermic process of melting.

32
Q

Heat flow

A

Is the energy required to keep the sample at the same temperature

33
Q

Heat flow is recorded with a sensitivity of

A

+/-0.1microcalories/s

34
Q

Melting of crystals is a …. Order reaction

A

First

35
Q

Melting is exo/endothermic

A

Endothermic ( the sample takes in the molar heat of fusion)

36
Q

ISM stands for

A

Isothermal micro calorimetry

37
Q

Principle of IMC is to monitor…..

A

Heat into/out of a sample cell, from/to a sink

38
Q

Sink is held isothermically with and accuracy of …. Improve to …. By…

A

+/- 10^-4
Use a reference cell to correct for variations
Brings it down to +/-10^-6

39
Q

Output is … As a function of time

A

Change of heat as a function of time

40
Q

ITC does/does not use temperature ramping

A

Does not

41
Q

ITC examines….

A

Solid state stability of tablets
Product interaction with stability studies
Wetting of drugs
Measuring enthalpy of immersion
Crystal properties (amorphous crystalline transitions)

42
Q

Advantages of ITM

A
  • DTS & DSM to determine rate of decomposition requires extrapolation of data to storage temperatures
  • ITM sensitivity can measure kinetics of product degradation in or,al storage conditions.
  • non distructive
  • not sample treatment required
  • real time quantitative data
  • obtains kinetic and thermodynamic data
  • can be used to monitor and physical, chemical or biological process
43
Q

ITM has …. Greater sensitivity than DCS

A

10,000

44
Q

Disadvantage of ITM

A

Need large sample size. 1000mg.

DSC 10mg

45
Q

Thermal studies allow….

A
  • characterisation of drug substances and formulations in qualitative and quantitative manner
  • allow optimisation of formulations
  • save time on stability studies
  • can be used for rate/mechanism/thermodynamic characterisation studies
46
Q

t/F Thermal analysis is In conjunction with other preformulation methods

A

T

47
Q

Crystallisation is endo or exo

A

Exo - sample is giving out energy

48
Q

Melting point transition is endo or exo?

A

Endo - sample is taking in energy to fuel reaction

49
Q

What valuable info do we get from therm anal 2

A

properties of materials and formulations.

An indication of a product stability and its interactions

Medicines design II - solid dosage forms (11 decks)

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