1process in which large particles are broken down into smaller particles. Often achieved by the use of high shear forces.
particle size reduction
2methods of particle size reduction
comminution
trituration
pulverization with intervention
levigation
3general term for various processes used to reduce the particle size of drug material by cutting/slicing, crushing/ contusion, grinding, sieving and trituration
comminution
4comminution by rubbing using a mortar and pestle. It is a mixture of one or more finely ground powdered drugs
trituration
5used with hard crystalline powders that do not crush or triturate easily
pulverization with intervention
6uses alcohol or actetone as a solvent that will dissolve the compound, and then mixed in a mortar, and evaporation of the solvent is carried out
pulverization with intervention
7trituration of a powder with an insoluble liquid (levigating agent)
levigation
8paste is formed by combining the powder and a small amount of liquid by which the powder is insoluble. Commonly used in small scale preparation of ointments and suspensions
levigation
9The process in which substance forms a solution
dissolution
10which method yielded a faster dissolution of solution
method B
11principle behind procedure A: dissolution
the particle size reduction causes an increase in the surface area of particles, allowing greater interaction with the solvent and imporivng dissolution
12reagent used in Activity 1_procedure A?
alum
13a list of values or a mathematical function that defines the relative amount of particles present, sorted according to size
particle size distribution (grain-size distribution)
14importance of analysis of particles and characterization of size and shape
size of granules have an effect on disintegration rate, dissolution rate and the absorbance rate
15method of particle size determination
sieving method
laser diffraction
dynamic light scattering
optical microscopy
16conceptually simple methods for deducing the partcle-size distirbution of a powdered solid. One simply passes the sample through wire meshes that have opening of various sizes
sieving analysis
17the process separates fine particles from more course particles by passing the material through a number of sieves of different mesh sizes
sieving analysis
18two types of sieve analysis
wet sieving
dry sieving
19sieving analysis suitable for particle sizes from 20 micro meter to 3 mm
wet sieving
20suitable sieving analysis for particles from 30 micrometer to 125mm
dry sieving
21mesh size opening suitable for very course particles
> 1000
22mesh size opening suitable for course particles
355-1000
23mesh size opening suitable for moderately course particles
180-355
24mesh size opening suitable for fine particles
125-180
25mesh size opening suitable for very fine particles
90-125
26mesh size numbers suitable for very course particles
2000/355
27mesh size numbers suitable for course particles
1000/355
28mesh size numbers suitable for moderately course particles
355/180
29mesh size numbers suitable for fine particles
180
30mesh size numbers suitable for very fine particles
125
31sieve analysis will not yield reliable mass results to what type of particles
elongted and flat particles
32disadvanatge of sieving analysis
no further particle shape information is available
does not have the ability to analyze single particles
has longer measurement time and lower measurement speed
are prone to binding
no particle images can be obtained using sieve analysis
33principle of laser diffraction
interaction of light with a particle
when light comes in contact with a particle, that incident light is altered in some way which is usually characteristic of the particle
34interactions that takes place in laser diffraction
reflection
refraction
absorption
diffraction
35disadvantage of laser diffraction
can result to erroneous measurement when incorrect refractive indices are selected
assumption that all particles are perfect spheres can reduce the accuracy of measurement
analysis of non-homogenous sample can result in incorrect measurements due to changing refractive index values
measurement times can range from 2-10 minutes
testing must be carried out offline which limits the use of laser diffraction
36other term for dynamic light scattering
quasielastic light scattering
photo correlation spectroscopy
37optical method of determining particle size properties within a disperse sample by observing the change in scattered light intensity as a function of time
dynamic light scattering
38offline method of partice size determination which is typically employed for particle sizes in the range of 0.002-2micrometer
dynamic light scattering
39what properties are dynamic light scattering sensitive to?
temperature
solvent viscosity
refractive index
contamination
40direct imaging particle size analyzer which measures size and shape information of particles in the size range of 50-5500 micrometer in real time
for ordinary microscope: 0.2 to 100 micrometer
An emulsion or suspension, diluted or undiluted, is mounted on a slide or ruled cell and placed on a mechanical stage
optical microscopy
41large scale methods of particle size reduction
pulverizers
grinders
homogenizers
42example of grinders
milling machines
43particles are reduced in size and passed through a screen of desired dimension to the collection container through the grinding action of rapidly moving blades in the comminuting chamber
grinders
44mixer used to create a unifrom and even mixture by forcing material through a narrow, confined space
homogenizers
45used with high shear mixers, batch mixers, and paddle mixers and are installed downstream to create finer mixtures
homogenizers
46reagent used in Activity 1_procedure B
boric acid
47characteristic related to inter-particulate friction or resistance to movement between particles. describes as the maximum angle at which an object can rest on an inclined plane without sliding down
angle of repose
48the maximum angle possible between the surfce of a pile of powder and the horizontal plane
angle of repose
49reagents used in Activity 1_procedure c
rock salt
fine salt
talc
50factors affecting angle of repose
particle size
particle shape
roughness of the particles
moisture
51use of glidant
decrease the frictional force and increace the flowability of solution
52example of glidant
colloidal silica
magnesium stearate
starch
talc