Jan 12 - Equipment

Question 1

Name four pieces of equipment used by pharmacists

Answer 1

Balances
Mortars and pestles
Spatulas
Volumetric glassware

Question 2

What is balance selection based on?

Answer 2

Nature of the material
Quantity of the material
Accuracy required

Question 3

Describe prescription balances. What is SR?

Answer 3

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

Question 4

Describe electronic balances

Answer 4

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

Question 5

How is a balanced used properly?

Answer 5

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

Question 6

When should electronic balances be calibrated?

Answer 6

Electronic balances must be calibrated when the balances are moved (at least)

Question 7

What is weight?

Answer 7

Weight is the force gravity exerts on a mass. The force of gravity varies with altitude?

Question 8

What is a tolerable percentage of error?

Answer 8

+/- 5%

Question 9

What is accuracy?

Answer 9

Accuracy is the extent to which a measure agrees with the true value

Question 10

How is the % of error calculated?

Answer 10

(Measured value-desired value) x 100/quantity desired

Question 11

What other considerations should be taken into account when using balances?

Answer 11

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

Question 12

How is the lower weighable quantity (LWQ) calculated?

Answer 12

Sensitivity (potential error) x 100/ % error tolerated

Question 13

What is trituration?

Answer 13

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

Question 14

Why do pharmacists dilute potent drugs with inert diluent powders?

Answer 14

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.

Question 15

What is geometric dilution?

Answer 15

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

Question 16

What are mortars and pestles?

Answer 16

Utensils commonly used for small scale comminution

Question 17

What is comminution?

Answer 17

The mechanical process of reducing particle size

Question 18

What are mortars and pestles made of?

Answer 18

They may be made of glass or porcelain

Question 19

Why would someone use a glass mortar and pestle?

Answer 19

Glass is used for soft powders, liquid incorporations or semi-solids like ointments. Glass is best for coloured materials and volatile oils

Question 20

Why would someone use a porcelain mortar and pestle?

Answer 20

Glazed porcelain is similar to glass but Wedgwood is somewhat rougher. Porcelain is for comminution of crystalline material and for primary emulsions

Question 21

What are spatulas made of?

Answer 21

They may be made of stainless steel or plastic

Question 22

When should steel spatulas be avoided?

Answer 22

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)

Question 23

What are spatulas used for?

Answer 23

They are primarily used for levigation of powders prior to incorporation into semi-solids (creams or ointments)

Question 24

What is levigation?

Answer 24

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

Question 25

What considerations should be made with regard to levigating/levigating agent?

Answer 25

The levigating agent must be compatible with the drug and vehicle
The two most common levigating agents are mineral oil (liq pet) and glycerin
Levigation may be done using a mortar and pestle to prepare suspensions

Question 26

What is pulverization by intervention?

Answer 26

A process whereby the material is mixed with an organic solvent (e.g. ethanol). The solution is poured onto a glass slab to allow the solvent to evaporate. A spatula scrapes the powder away from the glass. This process is used when to levigate gummy materials (such as camphor)

Question 27

What is volumetric glassware used for?

Answer 27

Used to measure exact quantities of liquids. All volumetric glassware are marked with capacity and have calibration marks for measuring. They may be “to deliver” (TD; e.g. pipettes) or “to contain” (TC; e.g. volumetric flasks)

Question 28

What is not considered volumetric glassware

Answer 28

Erlenmeyer flasks, beakers and prescription bottles (despite having graduate markings)

Question 29

What are pipettes used for?

Answer 29

Used to measure volumes smaller than 5 ml

Question 30

What are syringes used for?

Answer 30

They are used for both parenteral and oral use. They have good accuracy and range in size from 0.5 to 60 ml

Question 31

What do volumetric flasks range from?

Answer 31

From 1 to 5000 ml

Question 32

What are graduated cylinders used for?

Answer 32

They are used for measuring and transferring liquids when the volume is greater than about 2 ml

Question 33

What has better accuracy: cylindrical or conical graduated cylinders?

Answer 33

Cylindrical cylinders have better accuracy