Shared Flashcard Set

Details

Ceutics Exam 1, Part 2
Micromeritics
43
Pharmacology
Professional
01/27/2012

Additional Pharmacology Flashcards

 


 

Cards

Term
Define micromeritics
Definition
The science and technology of small particles
Term
Are all particles spherical?
Definition
No, they come in all forms and shapes
Term
Do all particles in the same powder have the same size?
Definition
No, in general there is a size range unless prepared by specialized technology
Term
How is particle area diameter measured?
Definition
Microscopy/sieving
Term
How is particle volume diameter measured?
Definition
Laser diffraction, light obscuration, coulter culture
Term
How is particle Stokes' diameter measured?
Definition
Sedimentation
Term
How is particle equivalent surface diameter measured?
Definition
Gas adsorption
Term
How is particle aerodynamic diameter measured?
Definition
Inertial impaction
Term
In to measure an irregular particle, what is a Feret diameter?
Definition
The diameter from the tip to the tip, as long as possible
Term
In to measure an irregular particle, what is a Martin diameter?
Definition
The diameter between two bisected parts (must measure consistently)
Term
In to measure an irregular particle, what is a projected diameter?
Definition
The diameter of a circle drawn around the particle
Term
Describe the process of sieving to determine particle size
Definition
A "nest" series of USP approved meshes with decreasing diameter are used so the smallest fall to the bottom

Size expressed as undersize, oversize, and mean particle size
Term
Give the equation for the drag force on a particle
Definition

(π/6)d3(ps-pf)g

 

d=diameter

g=gravity

ps=density of particle

pf=density of fluid

Term
Give the equation for terminal velocity of a particle in sedimentation
Definition
v=(d^2/18η)(ps-pf)g

(assumes all particles have same density, are spheres, flow laminar, and will not aggregate)
Term
How do you determine if a flow is laminar or turbulent?
Definition

If Re is less than .2, the flow is laminar

 

 

R=vdpf

Term
Describe the steps to analyze particle size via an Andreasen Pipette
Definition
1. A suspension is allowed to settle
2. Samples are taken at predetermined times, recording distance of fall
3. Fluid is evaporated from each sample and weight of particles are measured

Particle size is calculated by plotting the cumulative weight undersize
Term
What is the general principle of a sensor of volume diameter?
Definition
A particle is suspended or aerosolized within a region connected to a sensing mechanism that correlates instrument output with the volume of a particle
Term
How does a coulter counter measure volume/diameter?
Definition
A particle goes through an orifice and that is translated into voltage that is sent to a screen

(Smaller particles move more)
Term
How does a dynamic light scattering measure volume/diameter?
Definition
Movement of particles is detected by a laser sensor that reflects off them

(Smaller particles move more)
Term
How does a laser diffraction measure volume/diameter?
Definition
Particles are aerosolized into a region of a laser beam. As particles pass through a lens, the diffraction particle corresponds to size.

Smaller particles give larger diffraction intensity.

Diffraction pattern is different depending on shape.
Term
What are some disadvantages to automated methods to determine particle size?
Definition
Does not discriminate between individual particles and aggregates

Instruments are expensive, require maintenance and training
Term
If the ratio of αsv =6, what is the particle shape?
Definition
Sphere
Term
If the ratio of αsv >6, what is the particle shape?
Definition
An irregular shape
Term
How do you calculate Sv, the specific surface area per unit volume?
Definition
Surface area of particles/ volume of particles
Term
Define adsorption
Definition
The adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface
Term
How is gas adsorption used to calculate surface area?
Definition
It assumes that a monolayer of gas (nitrogen/helium) is adsorbed on the surface of particles when a sample of powder is placed on a container where gas is circulated

(Based on the Brunauer Emmett Teller equation)
Term
How does the Air Permeability Method calulate surface area
Definition
Surface area is proportional to the pressure drop or permeability of a fluid (usually air) flowing through a compacted sample of powder

(Based on the Kozeny-Carman equation)
Term
Define porosity
Definition
Porosity, or void fraction, is a measure of the void spaces in a powder

A fraction of the volume of voids in each particle over the total volume of the powder
Term
List some things that affect porosity
Definition
-Density
-Mixing different powders
-Packing arrangements
-Flow properties
-Compressibility
-Dissolution rate
-Aerodynamic properties
Term
What determines if a liquid will penetrate all the pores in a powder?
Definition
The density of a liquid and if the pores are connected
Term
Define true density
Definition
Density for the material itself, without pores or interparticulate spaces
Term
Define granule density
Definition
Density of the material itself, but considers pores >10μm and inter-particular spaces
Term
Define bulk density
Definition
Relationship of the volume occupied by a determined mass of powder
Term
Define tapped density
Definition
Relationship of the compacted volume occupied by a determined mass of powder
Term
Define pyncnometer
Definition
A gas or liquid machine to measure density based on Archimides' principle:

The weight of the displaced fluid is directly proportional to the volume of the displaced fluid
Term
How is porosity (ε) measured?
Definition
ε= 1- (ρ'/ρ)

ρ'= apparent or bulk density
ρ= true density
Term
Where is tapped density especially important?
Definition
In the field of inhalation
Term
What sort of things influence flow properties of powder?
Definition
-Size and distribution
-Shape
-Porosity
-Density
-Surface texture
Term
List some reasons why a powder would not flow smoothly
Definition
-Capillary forces (moisture)
-Van der Waals Forces
-Mechanical interlocking
-Electrostatic charge
Term
What is the Carr's compressibility index?
Definition
A relationship of bulk and tapped density
CCI= (ρT-ρ')/ρT

CCI>30 is a good indication that the powder will make a good tablet
Term
What is the angle of repose?
Definition
A way to measure powder flow, by creating a mountain of powder and seeing how steep the mountain side is
Term
List some ways to regulate powder flow
Definition
Granulation, formulating into particles, add glidants
Term
Define glidant
Definition
Something to add to large or granular powders to make it easier to flow

Ex. magnesium stearate, starch, talc
Supporting users have an ad free experience!