Jan 12 - Equipment Flashcards
Name four pieces of equipment used by pharmacists
Balances
Mortars and pestles
Spatulas
Volumetric glassware
What is balance selection based on?
Nature of the material
Quantity of the material
Accuracy required
Describe prescription balances. What is SR?
May be a beam on knife edge or torsion
Every licensed pharmacy must have one
The sensitivity is represented by sensitivity requirement (SR)
SR is the weight which will cause a specified change
Prescription balance must have SR of 6 mg
6 mg will cause a deflection of 1 unit on index plate
The capacity of a prescription balance 120 g
Describe electronic balances
They use electromagnetic force to restore beam to neutral
The electric current is proportional to the mass of an object
They are very quick and easy to use
They must be protected from electromagnetic fields
They may be affected by temperatures
They have wide range of capacity and sensitivity
How is a balanced used properly?
It should be kept on a level solid surface
The area should be kept free of vibration air movement and dust.
The balance should be calibrated
When should electronic balances be calibrated?
Electronic balances must be calibrated when the balances are moved (at least)
What is weight?
Weight is the force gravity exerts on a mass. The force of gravity varies with altitude?
What is a tolerable percentage of error?
+/- 5%
What is accuracy?
Accuracy is the extent to which a measure agrees with the true value
How is the % of error calculated?
(Measured value-desired value) x 100/quantity desired
What other considerations should be taken into account when using balances?
Material must never be weighed directly on the pain
Fixed weights must never touch fingers
Care must be taken to avoid spillage
Care must be taken to avoid cross-contamination (only have one container open at a time)
All materials must be identified at all times
How is the lower weighable quantity (LWQ) calculated?
Sensitivity (potential error) x 100/ % error tolerated
What is trituration?
A process of grinding a drug in a mortar with a pestle in order to reduce particle size or to blend powders. It may also refer to a blended mix of powders. It also refers to the dilution of a potent drug with an inert diluent powder
Why do pharmacists dilute potent drugs with inert diluent powders?
Powders are mixed in a definite proprotion by weight. This allows the removal of an aliquot which will contain the desired quantity of drug with acceptable accuracy.
What is geometric dilution?
The process used when a small amount of material is to be mixed with a much larger amount of solid or semi-solid material. Product homogeneity is very important and this technique is effective for mixing
What are mortars and pestles?
Utensils commonly used for small scale comminution
What is comminution?
The mechanical process of reducing particle size
What are mortars and pestles made of?
They may be made of glass or porcelain
Why would someone use a glass mortar and pestle?
Glass is used for soft powders, liquid incorporations or semi-solids like ointments. Glass is best for coloured materials and volatile oils
Why would someone use a porcelain mortar and pestle?
Glazed porcelain is similar to glass but Wedgwood is somewhat rougher. Porcelain is for comminution of crystalline material and for primary emulsions
What are spatulas made of?
They may be made of stainless steel or plastic
When should steel spatulas be avoided?
When working with materials that could corrode the metal, such as iodine or acids
When working with materials where trace amounts of metal may be harmful to the product (drugs or materials which oxidize easily, such as phenol)
What are spatulas used for?
They are primarily used for levigation of powders prior to incorporation into semi-solids (creams or ointments)
What is levigation?
The process of mixing powder with small amount of liquid (levigating agent) in which the powder is insoluble to make a smooth paste. The levigating agent aids in wetting of the powder. It’s a process used to reduce particle size and break down aggregates. It is often done with a flexible spatula on a glass slab
