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Powders Flashcards

1
Q

Essential in powder technology and dosage form design. Expressed as particle diameter

A

Particle size

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2
Q

The diameter measured from the length of the particles at the point that divides a particle into two equal projected areas.

A

Martin’s diameter

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3
Q

The average size of collection of particles

A

Mean diameter

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4
Q

Diameter for which 50% of particles are small and 50% are large

A

Median diameter

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5
Q

Represents the most frequent particle size

A

Mode diameter

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6
Q

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

A

Feret’s diameter

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7
Q

Method for determining feret’s diameter (df)

A

Microscopic method

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8
Q

Method for determination of martin’s diameter (dm)

A

Microscopic method

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9
Q

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

A

Projected area diameter (ds)

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10
Q

Method for determination of projected area diameter and perimeter diameter

A

Light extinction method

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11
Q

Diameter of a circle having the same perimeter as the projected outline particle

A

Perimeter diameter (dp)

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12
Q

Diameter of a sphere having the same volume as the particle

A

Equivalent volume diameter

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13
Q

Method of determination for equivalent volume diameter (dv)

A

Coulter counter method

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14
Q

Diameter of a sphere having the same surface area as the particle

A

Equivalent surface diameter

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15
Q

Method for determination of equivalent surface diameter (ds)

A

Surface method (absorption,permeability)

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16
Q

Width of the minumum square Aperture through which the particle can pass

A

Sieve diameter

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17
Q

Method for determination for sieve diameter (dA)

A

Sieving method

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18
Q

Diameter of a sphere having the same gravitational setting velocity as the particle

A

Equivalent light-scattering diameter

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19
Q

Method for determination of Equivalent light-scattering diameter (dIa)

A

Light scattering method

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20
Q

Diameter of a sphere having the same terminal settling velocity in the gas as the particle

A

Aerodynamic diameter

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21
Q

Method for determination of Aerodynamic diameter (dAero)

A

Impactor method

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22
Q

Expressed as the frequency distribution and the cumulative frequency distribution

A

Particle size distribution

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23
Q

Most precise particle size determination methods. Direct viewing of the particles. Sample size of atleast 300-600 particles. Analysis of two dimensional images of projected particles on a projection screen

A

Microscopic method

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24
Q

Used to characterize particle size between 1-150 microns in diameter

A

Light microscopy

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25
Q

Can aquire a three dimensional image of particles, particle shape and thickness.

A

Scanning electron microscopy

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26
Q

Used in particle size less than 1 micron in diameter

A

Transmission electron microscopy (TEM) scanning electron microscopy (SEM)

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27
Q

Rely on measuring the percentage by number or mass of the extracted size group corresponding to the feed concentration from the powder sample

A

Separation method

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28
Q

Most conventional and simplest separation method. Low cost and ease of operation. Arrange form coarser mesh opening to smaller mesh, top to bottom

A

Sieving

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29
Q

Wet sieving is designed for micron particle usually

A

6-150 um2

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30
Q

Defined as the width of minimum square aperture through which particle can pass through

A

Sieve diameter

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31
Q

Sources of error for sieving method

A
  • shape of the particles
  • weight of the sample loaded unto the sieve
  • vibration intensity
  • the phenomenon of static electricity cause by friction.
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32
Q

Measure the aerodynamic diameter of aerosols.

A

Impaction

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33
Q

An expression of a particle’s aerodynamic behavior and diameter. Way to characterize aerosols

A

Aerodynamic diameter.

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34
Q

Settling of a single particle in a liquid medium under the influence of gravitational and centrifugal forces

A

Sedimentation method

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35
Q

Particle settling in a liquid medium can be describe by

A

Stokes law

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36
Q

Commonly used instrument for sedimentation method

A

Andreasen pipette

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37
Q

Used to measure the particle size between 5-10um in diameter

A

Centrifugal sedimentation

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38
Q

Measures 0.6-120um particle size

A

Coulter counter method or electrical sensing zone

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39
Q

Based on facts that particles scatter light. Measure both large and small particles.

A

Laser light-scattering methods or laser diffraction

40
Q

Low angle light scattering is also referred as

A

Fraunhofer diffraction

41
Q

Fundamental theory of photo correlation spectroscopy (PCS)

A

Brownian motion

42
Q

The surface area of particles expressed per unit weight or volume.
Surface area increases as particle size decreases.

A

Specific surface

43
Q

Determination of surface area

A 
Gas adsorption ( 0.03-1um)
Permeability (1-100um)
44
Q

Developed the equation of sorption isotherms

A

Brunauer, emmett, and teller or the BET method

45
Q

Factors that affect the resistance of flow

A

Surface area of the powder
Surface area of the bed
Pore size
Viscosity of the fluid

46
Q

Slender, needle-like particle of similar width and thickness

A

Acicular

47
Q

Long,thin particle with a width and thickness that are greater than acicular

A

Columnar

48
Q

Thin, flat particle of similar length and width

A

Flake

49
Q

Flat particles of similar length and width but with greater thickness than flakes

A

Plate

50
Q

Long, thin, and blade like particles

A

Lath

51
Q

Particles of similar length, width and thickness, includes cubical and spherical particles

A

Equant

52
Q

Ratio of mass to volume

A

Density

53
Q

Types of particle shapes

A 
Acicular
Columnar
Flake
Plate
Lath
Equant
54
Q

Types of density

A

True density
Particle density
Bulk density

55
Q

The ratio of the mass of the particle to its actual volume, excluding pore volume and the volume gap between particles.

A

True density

56
Q

Determination of true density

A

Helium pycnometer

57
Q

Ratio of particle mass to the particle volume, including pores within the particle. Excluding gaps between particles

A

Particle density

58
Q

Determination method of particles density

A

Mercury intrusion method

59
Q

The ration of powder bed mass to volume of powder bed, includes both pore and gap volume

A

Bulk density

60
Q

Typical apparatus for liquid replacement method

A

Pycnometer

61
Q

Other method for particle density

A

Laser interferometer
Differential mobility analyzer
Sedimentation
Diffraction method

62
Q

Defined as fused or cemented particles

A

Agglomerate

63
Q

Mass of adhered particles

A

Aggregate

64
Q

Essential property for a powder.represents the void on the surface of individual particles or agglomerates of particles.

A

Specific surface area

65
Q

Method to determine surface are

A 
Gas adsorption 
Permeability
Flow microcalorimeters
Estimation of surface area from size distribution data
Turbidity method 
Chemisorption
66
Q

The ratioof the volume of the pore interior and the space between particles to the total volume of the powder, including the pore interior, the gaps between the particle, and the inherent volume of the particle

A

Porosity

67
Q

Affects porosity

A

Particle shape
Particle size
Surface properties
( fine particles -> porous -> faster disintegration time)

68
Q

Push a non-wetting liquid and cause it to enter into an extremely small volume, which requires extremely high pressure.

A

Capillary rise phenomenon

69
Q

State of powders

A

Crystalline

Amorphous

70
Q

Molecules in the solid are arranged in a fixed order. Exhibits melting point

A

Crystalline

71
Q

The outer appearance of a crystal

A

Crystal habit

72
Q

Molecules in a substance are packed in a non-fixed, random order. No melting point. Easy to disintegrate and dissolve.

A

Amorphous state

73
Q

The temperature at which of the solid transforms between rubbery to glassy.

A

Glass transition temperature

74
Q

Crystals with different packing orders. Obtained by changing the crystallization conditions. Like different solvent or changing direction of stirring

A

Polymorphism

stable form has high melting point and low dissolution rate.

75
Q

Has high dissolution rate and might be a candidate for enhancing the bioavailability of poorly soluble drugs.

A

Metastable polymorphic forms

76
Q

> Has been widely used to determine the crystallinity of solid powders.
Measurement of identical intensity patterns, composed of peaks at different scattering angle

A

Xray diffraction

77
Q

Also widely used to evaluate the crytallinity of solid powders.

A

Thermal analysis

78
Q

Frequently used. Plotted by differentiating the rate of heating versus temperature.

A

Differential scanning calorimetry

79
Q

Essential property that has a great impact on pharmaceutical process, like blending, transfer, storage, compression, and handling

A

Powder flowability

80
Q

Widely used to describe powder flowability.

The angle between the free surface of the powder body and the horizontal plane.

A

Angle of repose

Smaller angle of repose -> smaller frictional forces -> greater flowability

81
Q

Angle of repose less than 30 degrees

A

Free-flowing powder

82
Q

Less than 40 degrees

A

Satisfactory flowability

83
Q

Greater than 40 degrees

A

Does not flow freely

84
Q

A direct method to determine powder flowability, by measuring the rate of powder discharging from the hopper.

A

Hopper rate flow

85
Q

Particle size larger than 200um

A

Smaller angle of repose

86
Q

100-200um

A

Cohesion and friction increase . Angle of repose increases

87
Q

Less than 200um

A

Agglomeration occurs, particles exhibit tackiness or stickiness

88
Q

Particle size

A

Particle size increases -> less angle of repose -> better flowability

89
Q

Particle shape

A

Irregular particle shape -> rougher surface -> poor powder flowability

90
Q

Water content

A

Cohesive forces are related to the amount of water contained in the powder.
Increase angle of repose -> increase moisture content -> increase cohesive forces -> flowability decreases

91
Q

Like molecules are attracted to each other

A

Cohesive forces

92
Q

Different molecules are attracted to each other

A

Adhesive force

93
Q

Are Powders consisting of very fine particles. Fill the hollow parts on the powder surfaces. To much of it can cause poor powder flowability.

A

Lubricants and glidants

94
Q

Phenomenon where Molecules or ions are transferred from solid into solution

A

Dissolution

95
Q

Extent of dissolved substance

Amount of substance in a solution when equilibrium is achieved between the dissolved and non-dissolved substance.

A

Solubility

96
Q

Dissolution rate, independent of agitation speed, surface area, diffusion layer thickness, and the volume of solvent

A

Intrinsic dissolution rate

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