BANGABANDHU SHEIKH MUJIBUR RAHMAN
SCIENCE AND TECHNOLOGY UNIVERSITY
GOPALGANJ-8100
AN ASSIGNMENT ON
Course Title
: Pharmaceutical Technology - 2
Course code
: ACCE-305
Topic
: EMULSION
Date
: 09-07-2021
Submitted By
Name: Aqib Adnan Shafin
Student ID: 17ACE034
Session: 2017-2018
3rd Year 1st Semester
Department: Applied
Chemistry & Chemical
Engineering, BSMRSTU,
Gopalganj-8100.
Submitted To
Name: Rifat Ara Masud
Lecturer
Department: Applied
Chemistry & Chemical
Engineering, BSMRSTU,
Gopalganj-8100.
1
INDEX
TOPICS
PAGE NO.
What is Emulsion?
2
Types of Emulsion
2-3
Pharmaceutical Applications of Emulsions
4
Identification Tests for Types of Emulsions
4-7
Bancroft’s Rule
7-9
Reference
9-10
2
EMULSION
 An Emulsion is a thermodynamically unstable system consisting of two immiscible
liquid phases, one of which is dispersed/ distributed as globules/droplets (internal or
dispersed phase) in the other liquid medium (external or continuous phase) stabilized
by a third substance called an emulsifying agent [1].
Fig : Emulsion[2]
The two well known examples of emulsions are[1] :
1) Milk in which the particles of the liquid fat are dispersed in water.
2) Cod liver oil emulsion in which water is dispersed in the oil.
 By considering particle size, pharmaceutical emulsions can be [3] :
 Macroemulsions (droplets size usually exceeds 10 mm)
 Miniemulsions (droplets size usually 0.1–10 µm)
 Microemulsions (droplets size usually 100-600 nm)
 Nanoemulsions (droplets size usually below 100 nm)
 Types of emulsion : Emulsions typically consist of a polar (e.g., aqueous) and a
relatively nonpolar (e.g., an oil) liquid phase[3]. The two basic types of emulsions are[3]
–
1) Oil-in-water (O/W) emulsion : If the oil droplets are dispersed throughout the
water phase, the emulsion is called oil in water (O/W) [2].
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Fig : Oil-in-water (O/W) emulsion[2]
2) Water-in-oil (W/O) emulsion : If the water droplets are dispersed throughout
the oil phase, the emulsion is called oil in water (W/O)[2].
Fig : Water-in-oil (W/O) emulsion[2]
However, depending upon the need, more complex systems referred to as “double
emulsions” or “multiple emulsions” can be made[3]. Multiple emulsions are complex
systems. They can be viewed as emulsions of emulsions. It is a complex type emulsion
system in which the oil-in-water or water-in-oil emulsions are dispersed in another
liquid medium[2].
Fig : Multiple emulsions[2]
4
a) Pharmaceutical application of emulsions :

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Emulsions are used to improve effectiveness by controlling dosage of active
ingredients and to provide improved aesthetics for topical drugs such as ointments.
Nonionic emulsions are most popular due to their low toxicity, ability to be
injected directly into the body and compatibility with many drug ingredients.
Cationic emulsions are also used in certain products due to their antimicrobial
properties[4].
Multiple emulsions have been formulated as cosmetics, such as a skin
moisturizer[2].
Emulsions (macroemulsions and microemulsions) are generally well documented
as carriers for hydrophilic and lipophilic drugs[3].
Oils and drugs having objectionable taste or texture can be made more palatable
for oral administration by formulating into emulsions. As a result, mineral oilbased laxatives, oil-soluble vitamins, vegetable oils, high-fat nutritive preparations
for enteral feeding and certain drugs such as valproic acid are formulated
frequently in an oil-in-water (o/w) emulsion form[3].
With topically applied emulsions, the formulation scientist can control the
viscosity, appearance and degree of greasiness of cosmetic and dermatologic
products. o/w emulsions are most useful as water-washable bases, whereas waterin-oil (w/o) emulsions are used widely for the treatment of dry skin and emollient
applications to provide an occlusive effect [3].
Semisolid preparations, such as ointments and creams, represent the dispersions of
liquids in solids, which are used topically[3].
Emulsions are also employed in many other clinical applications as radiopaque
emulsions and parenteral emulsions and in blood replacement therapy[3].
Water insoluble compounds are orally administered as o/w emulsion with pleasant
taste e.g. vitamin A, E, D and K are absorbed more quickly when emulsified [5].
Some therapeutic agents show bioavailability more when given in the form of
emulsions e.g. heparin and insulin[5].
Non-absorbable macromolecules are absorbed to small extent when given orally
as such insulin and heparin and they may even be digested in stomach. But when
these agents are given in emulsified form they are not digested and are fully
absorbed[5].
The intravenous fat emulsions are used to supply or deliver isotonic liquids in small
amount i.e. volume to provide large amount of energy to the body. The fat
emulsions for intravenous nutrition generally contain vegetable oil, a phospholipid
and emulsifying agent. The examples are: Intralipid, Lipofundins and
Lipofunduns[5].
b) Identification tests for types of emulsion :
Since emulsion (o/w or w/o) looks the same in appearance with naked eyes, therefore
certain tests have been developed to differentiate between them[2]. It is also important that
at least two tests should be performed to draw a final conclusion[6].

Dilution test : In this test the emulsion is diluted either with oil or water. If the
emulsion is o/w type and it is diluted with water, it will remain stable as water is
5
the dispersion medium but if it is diluted with oil, the emulsion will break as oil
and water are not miscible with each other. Oil in water emulsion can easily be
diluted with an aqueous solvent whereas water in oil emulsion can only be diluted
with a oily liquid[6].
Fig : Dilution Test[7]

Conductivity Test : The basic principle of this test is that water is a good
conductor of electricity. Therefore, in case of o/w emulsion, this test will be
positive as water is the external phase. In this test, an assembly is used in which
a pair of electrodes connected to an electric bulb is dipped into an emulsion. If the
emulsion is o/w type, the electric bulb glows[6].
Fig : Conductivity Test [8]

Dye Solubility Test : In this test an emulsion is mixed with a water soluble dye
(amaranth) and observed under the microscope. If the continuous phase appears
red, it means that the emulsion is o/w type as water is in the external phase and
the dye will dissolve in it to give color. If the scattered globules appear red and
continuous phase colorless, then it is w/o type. Similarly, if an oil soluble dye
6
(Scarlet red C or Sudan III) is added to an emulsion and the continuous phase
appears red, then it is w/o emulsion[6].
Fig : Dye Solubility Test [8]

Cobalt chloride paper test : Cobalt chloride blue paper turns pink when
hydrated[2]. When the filter paper soaked in cobalt chloride solution is dipped in
to an emulsion and dried, if it turns from blue to pink, it indicates that the emulsion
is o/w type[6].
Fig : Cobalt chloride paper test [9]

Fluorescence test : Oil gives fluorescence under UV light, while water does
not[2]. If an emulsion on exposure to ultra-violet radiations shows continuous
fluorescence under microscope, then it is w/o type and if it shows only spotty
fluorescence, then it is o/w type[6].
7
Fig : Fluorescence test [10]

Formation of creaming : Creaming is the upward/downward movement of
dispersed droplets of emulsion relative to the continuous phase, due to the density
difference between two phases. Upward creaming occurs if the dispersed phase is
less dense than the continuous phase. This is normally observed in o/w emulsions.
Downward creaming occurs if the dispersed phase is heavier than the continuous
phase. Due to gravitational pull, the globules settle down. This is normally
observed in w/o emulsions[8].
Fig : Formation of creaming[1]
c) Bancroft’s Rule :
The Bancroft rule states : "The phase in which an emulsifier is more soluble constitutes
the continuous phase[11]."
It was named after Wilder Dwight Bancroft, an American physical chemist, who proposed
the rule in the 1910s[11].
In all of the typical emulsions, there are tiny particles (dispersed phase) suspended in a
liquid (continuous phase). In an oil-in-water emulsion, oil is the dispersed phase, while
water is the continuous phase[11].
What the Bancroft rule states is that contrary to common sense, what makes an emulsion
oil-in-water or water-in-oil is not the relative percentages of oil or water, but which phase
the emulsifier is more soluble in. So even though there may be a formula that's 60% oil and
40% water, if the emulsifier chosen is more soluble in water, it will create an oil-in-water
system. It's a very useful rule of thumb for most systems[11].
Emulsifiers/Emulsifying agents are amphiphilic in nature i.e., they have polar & nonpolar
8
group. They stabilize emulsion by preventing/reducing the coalescence of dispersed
globules[1].
Fig : Illustration of Bancroft’s Rule[1]
The hydrophilic-lipophilic balance of a surfactant is a measure of the degree to which it is
hydrophilic or lipophilic, determined by calculating values for the different regions of the
molecule, as described by Griffin[12]. The hydrophilic-lipophilic balance (HLB) of a
surfactant can be used in order to determine whether it's a good choice for the desired
emulsion or not [11].
Fig : HLB Scale[12]

In oil-in-water emulsions – use emulsifiers that are more soluble in water than in
oil (High HLB surfactants)[11].
9

In water-in-oil emulsions – use emulsifiers that are more soluble in oil than in
water (Low HLB surfactants)[11].
Bancroft’s Rule describes the relationship between the nature of the emulsifying
agent/emulsifier and type of emulsion formed[1]. Based on the Bancroft’s rule, it is possible
to change an emulsion from O/W type to W/O type by inducing changes in surfactant’s
HLB. In other words, phase inversion may be induced[13].
Reference :
[1]
“Pharmaceutical Emulsion | The Pharmapedia.”
http://thepharmapedia.com/pharmaceutical-emulsion/pharmacy-notes/ (accessed Jun.
28, 2021).
[2]
“PHARMACEUTICAL EMULSIONS - knowledgeabletutorial.”
https://www.knowledgeablefact.com/pharmaceutical-emulsions/ (accessed Jun. 28,
2021).
[3]
“Pharmaceutical Emulsions: An Overview - Pharmapproach.com.”
https://www.pharmapproach.com/pharmaceutical-emulsions-an-overview/ (accessed
Jun. 28, 2021).
[4]
“Emulsion - Uses Of Emulsions - Water, Hair, Soluble, and Products - JRank
Articles.” https://science.jrank.org/pages/2461/Emulsion-Uses-emulsions.html
(accessed Jun. 30, 2021).
[5]
“SPECIALIZED PHARMACEUTICAL EMULSIONS.”
http://infolounge107.blogspot.com/2018/02/specialized-pharmaceuticalemulsions.html (accessed Jun. 30, 2021).
[6]
“Tests for Identification of Emulsion Types.”
https://www.preservearticles.com/education/tests-for-identification-of-emulsiontypes/16986 (accessed Jun. 30, 2021).
[7]
“Pharmaceutical emulsion - ppt download.” https://slideplayer.com/slide/14041699/
(accessed Jul. 02, 2021).
[8]
O. Upton, “Pharmaceutical Emulsions - Department of Pharmacy GP (Uttawar),”
Techniques, no. Rar 806, pp. 1–5, 2012.
[9]
“What is the relationship between milk and emulsion? PH ppt download.”
https://slideplayer.com/slide/10977922/ (accessed Jun. 30, 2021).
10
[10] “Alfred Martin Lecturer: Dr. Majid R. Feddah - ppt download.”
https://slideplayer.com/slide/14230159/ (accessed Jun. 30, 2021).
[11] “Bancroft rule - Wikipedia.” https://en.wikipedia.org/wiki/Bancroft_rule#cite_note-4
(accessed Jun. 30, 2021).
[12] “Hydrophilic-lipophilic balance - Wikipedia.”
https://en.wikipedia.org/wiki/Hydrophilic-lipophilic_balance (accessed Jun. 30, 2021).
[13] “Colloid Chemistry,” Colloid Chem., 2019, doi: 10.3390/books978-3-03897-460-4.