Micromeritics

Physical Pharmacy

1. MICROMERITICS Kiran C Rodge Shivlingeshwar college of Pharmacy, Almala, Tq-Ausa,Dist-Latur,Maharashtra

2. “ Micromeritics involves the study of characterstics of powder particle” By J . M. Dalla Valle

3. Application of micromeritics Absorption and drug action Release and dissolution Physical stability Dose uniformity

4. Particle characteristics Size Shape Surface area

5. Size of Particle

6. How to find out size of any particle ?

7. Diameter of asymetrical particle Projected diameter (d p )… is the diameter of a sphere having same area as same as of the asymmetric particle observed under a microscope. S urface diameter (d s )… is the diameter of a sphere having the same surface area as same as of the asymmetric particle. V olume diameter (d v )… is the diameter of a sphere having same volume as as same as of the asymmetric particle.

8. Diameter of asymetrical particle Volume-Surface diameter ( d vs )… is the diameter of a sphere that has same volume to surface area ratio as same as of the asymmetric particle. Stokes diameter ( d st )… is the diameter of a sphere having the same sedimentation rate as same as of the asymmetric particle. Sieve diameter ( d sieve )… is the diameter of a sphere that passes through the same sieve aperture as same as of the asymmetric particle.

9. P ARTICLE SIZE DETERMINATION METHODS

10. PARTICLE SIZE DETERMINATION METHODS Optical Microscopy Sieving Method Sedimentation Method Conductivity Method

11. Optical Microscopy Method Particle size in the range of 0.2 – 100 𝜇m can be estimated. Particle size is expressed as dp (projected diameter). It is used to estimate particle size of suspension, emulsions and aerosols .

12. Procedure Eye piece of the microscope is fitted with a micrometer. This eye-piece micrometer is calibrated using a standard stage micrometer. The powder sample is dispersed in a suitable vehicle in which it does not dissolve and its properties are not altered. ( eg . water, paraffin oil .) This sample is mounted on a slide and placed on the stage under the objective of microscope. Around 625 particles are visualized. their diameter is noted and mean is computed.

13. Advantages  and Disadvantages One can view particles Any aggregates detected Contamination of particles detected Use of cover slip for arresting motion of particles Easy and simple Length and breadth can be detected but depth or thickness of particles cannot be measured Slow- time consuming , tedious, inaccurate Number of particles to be measured is more Large sample required

14. Sieving Method Particle size in the range of 50 – 1500 𝜇m can be estimated. Particle size is expressed as d sieve (Sieve diameter). It is used to estimate particle size of any powder.

15. Procedure Arrange 6 sieve set in increasing order on mechanical sieve shaker.. Pour 100 gm powder sample on top most sieve & run shaker for 10 min. After 10 min weight the powder sample retain on each sieve

16. Grading of Powder Grade of Powder Specification Coarse Powder 10 / 44 Moderately Coarse Powder 22 / 60 Moderately Fine Powder 44 / 85 Fine Powder 85 Very Fine Powder 120

17. Sedimentation Method Particle size in the range of 1 – 200 𝜇m can be estimated. Particle size is expressed as d stokes (Stokes diameter). It is used to estimate particle size of Suspension , Emulsion & polydisperse particles.

18. Andreasen pipette method: One of the most popular of the pipette methods was that developed by Andreasen and Lundberg and commonly called the Andreasen pipette. In this method , known volumes of suspension are drawn off and the concentration differences are measured with respect to time. It involves measuring the % of solids that settle with time in a graduated vessel.

19. Andreasen pipette method

20. Sample preparation Powder is dispersed in a suitable solvent (1or 2 % ) If the powder is hydrophobic, it may be necessary to add dispersing agent to aid wetting of the powder. In case where the powder is soluble in water it will be necessary to use non- aqueous liquids or carry out the analysis in a gas.

21. Construction The Andreasen fixed-position pipette consists of a 200 mm graduated cylinder which can hold about 500 ml of suspension fluid. A pipette is located centrally in the cylinder and is held in position by a ground glass stopper so that its tip coincides with the zero level. A three way tap allows fluid to be drawn into a 10 ml reservoir which can then be emptied into a beaker or centrifuge tube

22. Method   A 1 or 2 % suspension of the powder in a suitable liquid medium is placed in the pipette. At a given intervals of time, samples are withdrawn from a specified depth without disturbing the suspension. The amount of powder can be determined by weight following drying or centrifuging .

23. Calculation Where, h = Distance of fall in time t η 0 = Viscosity of medium δ s = Density of the particles δ o = Density of dispersion medium g = Acceleration due to gravity t = time

24. Conductivity Method Particle size in the range of 0.5 – 500 𝜇m can be estimated. Particle size is expressed as d v (Volume diameter). It is also known as Coulter counter Method & Stream scanning method

25. Coulter counter Method

26. SHAPE of Particle

27. Shape of particle

28. Shape factor Shape factor is nothing but a ratio of surface area factor ( α s ) to the volume factor ( α v )

29. Surface Area of Particle

30. Surface Area of Particle Specific Surface is defined as the surface area per unit weight ( S w ) or unit volume( S v ) of the material …

31. Methods for determination of surface area Adsorption Method Particles having large specific surfaces are good adsorbents of gases and solutes from solution. Amount of gas that is adsorbed to form a Monomolecular layer on the adsorbent is a function of surface area of the powder. This principle is used to estimate specific Surface. This method is also used to estimate surface diameter ds..

32. Methods for determination of surface area Air Permeability method / Fisher subsieve sizer instrument

33. Mean of particle size

34. Mean of particle size Arithmetic Mean Geometric Mean Harmonic Mean

35. Arithmetic Mean Arithmetic mean of a powder is defined as the sum of the particle sizes divided by the number of particles. The powder, though polydisperse, can be expressed as its arithmetic mean i.e., it is made into a collection of uniform particles.

36. types Arithmetic Mean sizes 1) 2) 3)

37. types Arithmetic Mean sizes 4) 5 )

38. Geometric Mean

39. Particle number

40. Particle Size distribution Data are Expressed as Number Distribution Values Weight Distribution Values

41. powder DISIRIBUTION CURVES Frequency Distribution Curve Log-Normal Distribution Curve Cumulative Frequency Distribution Curve

42. Frequency Distribution Curve

43. Log-Normal Distribution Curve

44. Cumulative Frequency Distribution Curve

45. Derived Properties of powder

46. Derived Properties of powder Weight of powder True Density = True volume of powder Bulk Density = Mass of powder Bulk Volume

47. Derived Properties of powder Weight of powder Tapped Density = Tapped volume of powder Porosity ( ε ) = Bulk volume – True volume Bulk Volume

48. Derived Properties of powder Tapped Density Hausner's Ratio = Bulk Density Car’s Index= Tapped Density – Bulk density Tapped Volume x 100

49. Derived Properties of powder Angle of repose

50. Thanks! any questions ?