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Physical Pharmacy > Micromeritics > Flashcards

Micromeritics Flashcards

1
Q

Science of small particles and study of particle size distribution

A

Micromeritics

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2
Q

Unit of Particle Size

A

Micrometer
Nanometer

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3
Q

Fundamental properties of powders

A

Particle Size and size distribution
Volume
Number
Shape
Surface Area

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4
Q

Derived Particle Properties

A

Bulk Density, Granule Volume, Porosity

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5
Q

Methods of particle size determination

A

Optical Microscopy
Sieving Method
Sedimentation Method
Automated particle Counter

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6
Q

Most accurate method for particle size determination; microscope eyepiece is fitted with a micrometer where the diameter can be measured

A

Optical Microscopy

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7
Q

Range of Analysis for Optical Microscopy

A

0.2 um to 100 um

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8
Q

Advantages of Optical Microscopy

A

Direct observation of shape and size
Aggregation of particles can be detected
The field can be projected and a photograph can be taken
Easy to handle

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9
Q

Disadvantages of Optical Microscopy

A

Diameter is obtained from only 2D
No estimation of depth or thickness
Slow, tedious, time-consuming

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10
Q

3 Expression of Diameter

A

Martin’s
Ferret’s
Projected Area of Circle

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11
Q

Distance between pairs of parallel tangents to the projected outline of the particle in fixed directions

A

Feret’s Diameter

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12
Q

Diameter measured from the length of the particle at the point that divides a particle into two equal projected areas

A

Martin’s Diameter

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13
Q

Diameter of a circle having the same area as the projected area of the particle resting in stable position

A

Projected area diameter

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14
Q

Range of analysis of Sieving Method

A

50um to 1500um

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15
Q

Advantages of Sieving Method

A

Specially useful for weight distribution
Inexpensive
Simple

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16
Q

Disadvantages of Sieving Method

A

Sample should be dried every time
Induction of attrition during shaking -> reduction of particle size
Very small particles cannot be used

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17
Q

Used for evaluation of suspension, emulsions, and determination of molecular weight of polymers

A

Sedimentation Method

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18
Q

Sedimentation Rate is based on

A

Stoke’s Law

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19
Q

Instrument used in Sedimentation Method

A

Andreasen Pipet/Apparatus

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20
Q

Electrical resistance of a conducting liquid is increased by the addition of an insulating material

A

Coulter Counter

↑ Electrical Resistance
↑ Particle Vol ↑ Particle Size

21
Q

Single particle optical counter

Count particles rather than size

A

Light Blockage

↑Light Blockage ↑ Particle Size

↓Transmitted Light

22
Q

Measure of the void volume in a powder material

A

Porosity/Void Fraction

23
Q

Represents the fraction of the powder volume that is occupied by the voids

A

Porosity/Void Fraction

24
Q

Types of Porosity

A

Intraparticle
Interparticle

25
Q

Space within the particle

A

Intraparticle space or voids

26
Q

Space between the particle

A

Interparticle space/voids

27
Q

Types of Volume

A
  1. True Volume/ Particle (Vp)
  2. Granular Volume (Vg)
  3. Bulk Volume (Vb)
28
Q

Volume of the solid particles excluding both Intra and Inter particulate voids

A

True Volume (Vp)

29
Q

True volume of the particle with Intraparticle space or voids

A

Granule Volume (Vg)

30
Q

True volume of the particle with both Intraparticle and Interparticle space or voids

A

Bulk volume (Vb)

31
Q

Intraparticle Porosity Formula

A

𝑉𝑔−𝑉𝑏
_________________×100
𝑉𝑔

32
Q

Interparticle Porosity

A

𝑉𝑏−𝑉𝑔
______________ ×100%
𝑉𝑔

33
Q

Total particle

33
Q

Total particle Porosity

A

𝑉𝑏−𝑉𝑝
————— ×100%
𝑉𝑏

34
Q

Mass per unit volume

35
Q

Density determined using Helium densiometer

A

True Density (p)
p = m/v

36
Q

Density determine using Liquid Displacement

A

Granule density (pg)
p = m / Vg

37
Q

Density determined using Graduated Cylinder

A

Bulk Density (pb)
p = m / Vb

38
Q

Reciprocal of Density

A

Specific Volume

39
Q

Reciprocal of Bulk Density

A

Bulkiness or Specific Bulk Volume
↑Bulkiness ↓Particle Size

40
Q

Characteristics of Powder with Good Flowability

A

Inc. Particle Size
Smooth Surface
High Density
Low internal porosity
Low Electrostatic Charge
Spherical Shape
Low temperature

41
Q

Characterization of Powder Flow

A

Angle of Repose
Compressibility Index

42
Q

Maximum angle possible between the surface of a pile powder and horizontal plane

A

Angle of Repose

43
Q

Angle of Repose

A

tan𝜃= h/r

44
Q

Angle of repose and Flowability

A

Excellent <25
Good 25-30
Poor 30-40
Very Poor >40

45
Q

Angle of Repose and Flowability

A

Excellent 25 - 30
Good 31 - 35
Fair 36 - 40
Passable 41 -45
Poor 46 - 55
Very Poor 56 - 65
Very, very poor >66

46
Q

Ability to decrease in volume under pressure

A

Compressibility

47
Q

Carr’s Compressibility index

A

𝑉𝑜−𝑉𝑓
—————-𝑥 100
𝑉𝑜

48
Q

Hausner’s Ratio

A

𝑉𝑓
or
Tapped Density
————-
Bulk Density

Physical Pharmacy (14 decks)

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