EMULSIONS
An emulsion consists of two phases, one of which is finely divided and dispersed in the continuous
phase. The system is stabilized by the presence of a third substance known as the emulsifying
agent.
Types of Emulsion
1. Oil-in-water emulsions O/ W: The internal phase/dispersed phase is oil and external/
continuous phase is water.
2. water-in-Oil emulsions W/O: The internal phase/dispersed phase is water and external/
continuous phase is oil.
Methods for Preparing Emulsions:
One of the following general methods is employed:
I.
The Dry Gum Method
II.
The Wet Gum Method
The Dry Gum Method/wet gum method
 In this method, a primary emulsion is made from certain proportion of oil,
water and gum.
 Type of method is depending on the order of addition of gum, water and oil.
 When a stable primary emulsion has been obtained, it may be freely diluted with
more of the continuous phase (water in o/w emulsions).
 Any salts or flavoring agents are added in dilute solutions just before adjusting the
volume.
The Quantities for primary emulsions
A. Fixed oil, e.g., almond, castor, arachis and cod liver oil.
Oil : water : gum
4 : 2
: 1
B. Volatile oil, e.g., turpentine, cinnamon and peppermint oil.
Oil : water : gum
2 : 2
: 1
C. Mineral oil (liquid paraffin).
Oil : water : gum
3 : 2
: 1
 Internal emulsions prepared by the dry gum method should contain, in addition to the oil
to be emulsified, the following ingredients:
* A vehicle – freshly boiled and cooled purified water is normally used because of the
increased risk from microbial contamination.
* A preservative (usually added to the product as Double Strength Chloroform Water
BP at 50% of the volume of the vehicle). If freshly boiled and cooled purified water is
used as the vehicle, it would be appropriate to manufacture the Double Strength
Chloroform Water BP using freshly boiled and cooled purified
water rather than potable water
* An emulsifying agent (or emulgent). The quantity of emulsifying agent added is
determined by the type of oil to be emulsified and the quantity of emulsion to be
prepared.
* Additional flavouring if required.
* Additional colouring if required
HLB determination
An arbitrary scale was devised by the scientist Griffin to serve as a measure of the hydrophilic –
lipophilic balance (HLB) of surfactant. By means of this scale it is possible to assign a HLB
range of optimum efficiency for each class of surfactant.
The hydrophilic surfactant has the HLB value 10-18, and lipophilic surfactant have the HLB
value less than 10.
Required HLB value: It has be found that certain emulsifying agents of a given HLB value
appear to have the best effect when used in combination with particular oil phase.
It has given rise to the concept of Required HLB for given oil or oil combination, which is
defined as the HLB value that is required to prepare a stable emulsion of particular type.
Thus for a given oil, the RHLB of preparing a stable O/W emulsion can be different from that
required to prepare a stable W/O emulsion.
Experiment 1
AIM: To determine emulsifying agent on the basis of HLB value of surfactant and prepare and
submit 100 gm mineral oil emulsion.
Apparatus: Mortar pestle, beaker (250 ml), measuring cylinder (10 ml. 50 ml), Spatula and
glass rod.
Materials: Tween 80, Span 80, liquid paraffin, wool fat.
HLB Determination
The following example illustrates the use of HLB to determine the proportions of two
surfactants:

Polysorbate 80 with HLB = 15

Sorbitan monoolate with HLB = 4.3
Which are used as emulsifying agent in the following o/w and w/o systems:
Mineral oil
Rx
Liquid paraffin (required HLB=12)
30 gm
Wool fat (required HLB=10)
5 gm
Emulsifying agent
Water to
5 gm
100 gm
Mitte (send): 100 g
Uses: used as lubricant laxative
Sig (directions for use): take on empty stomach, at least 1 hr before and 2 hr after meal
Dose: 1 or 2 spoonful and add small amount of water (less than 30 ml)
Calculation: - For O/W emulsion
Liquid paraffin (required HLB=12)
Wool fat (required HLB=10)
Calculation: - For W/O emulsion????
Liquid paraffin (required HLB=5)
Wool fat (required HLB=8)
Procedure:
1) The oil-soluble SPAN is dissolved in the oil and heated to 75°;
2)
The water-soluble Tween is added to the aqueous phase that is heated to 70°.
3)
At this point the oil phase is mixed with the aqueous phase and the whole is stirred
continuously until cool.
Practical Lab Report
Name of Experiment:
Date:
AIM:
Ingredient used and their function:
Calculations:
Experiment 2
AIM: To prepare and submit 40 ml of castor oil.
Apparatus: Mortar pestle, beaker (250 ml), measuring cylinder (10 ml. 50 ml), Spatula and
glass rod
Materials: castor oil, gum acacia, water.
Fixed Oil
Formula:
Castor Oil Emulsion
Rx
Castor oil
16 ml
GUM acacia
Q.S.
Water
80 ml (q.s.)
F.: emuls
Sig. Stat
Uses: Castor oil is administered orally as a purgative.
Castor oil is a fixed oil. Therefore, the primary emulsion
Formula used is:
Oil: water: gum
4:
2
:1
Either the dry gum method or the wet gum method can be used, but the former is more suitable.
Method of preparation (dry method)
1. Select a suitable mortar and pestle.
2. Place in the mortar 2 g. acacia (very finely pulverized).
3. Measure 8 ml of oil in a dry measure and pour on the gum allowing some time for the measure
to drain.
4. Triturate the oil and gum together for a few seconds.
5. Measure exactly 4 ml of water in another measure.
6. Begin to triturate the oil and, gum again, and add water all at once.
7. As the water reaches the oil-gum mixture, increase the rate of trituration and work in
one direction only.
8. Continue trituration till the primary emulsion is formed. This is when the mixture becomes
white in colour and cracking sound is heard.
9. Continue to triturate for a little longer before attempting to dilute.
10. Measure small amount of water and add them drop wise, with continuous trituration, to the
primary emulsion and then dilute with remaining amount of water and transfer to a measure.
11. Rinse the mortar with more water and adjust the volume.
Castor oil emulsion USP (40 ml)
Formula:
Castor oil : ??
gum acacia : ??
Water : ??
Uses: used as purgative
Direction for Use:
immediately
Dose : swallow in one
time
Secondary Label: shake
well before use
Storage : Store in tight closed
Container.
Batch No:
Date of Manufacturing:
Date of Expiry:
Manufactured By:
Practical Lab Report
Name of Experiment:
Date:
AIM:
Ingredient used and their function:
Calculations:
Results
Indication:
No
1
2
3
Exp
name
Dry and
wet
method
Castor
oil
emulsion
Cod
liver oil
emulsion
Link
https://www.youtube.com/watch?v=4Bw7ug5X7zg&t=15s&ab_channel=Jaco
bVogel
https://www.youtube.com/watch?v=zp7pPSwFMw8&ab_channel=CHAMEL
IDEVIINSTITUTEOFPHARMACYINDORE
https://www.youtube.com/watch?v=TJWBM8KdZtw&ab_channel=nizamgh
ani
Dr. Yousef HAJYOUSEF
Faculty of Pharmacy
Cyprus International University