Emulsion

Sarder Istiaque Ahmed111-29-308

Daffodil International University

• A mixture of two or more liquids that are normally Immiscible.

• One liquid phase is dispersed is dispersed as globules in the other liquid phase.

Advantages• Mask the unpleasant taste.• Sustained

release medication.• Inert and chemically non-

reactive. • Reasonably odorless and

cost effective.

Disadvantages• Thermodynamically

unstable and have short shelf-life.

• Leads to creaming and cracking .

• leads to phase inversion.

Phase in Emulsion

• The dispersed liquid is known as the Internal or Discontinuous phase.

• The dispersion medium is known as the External or Continuous phase.

Types Of Emulsion

Oil in Water (O/W)Water in Oil (W/O)Water in Oil in water emulsion. Based on size of liquid droplets: Macroemulsions (0.2 – 50 mm)Microemulsions (0.01 – 0.2 mm)

Identification Tests For Emulsion Dye test. Dilution test. Electrical conductivity test. Fluorescence test. Cobalt chloride test.

Emulsifying Agent• Soluble in both oil and water and enable oil to be uniformly dispersed in

water as an emulsion.• Emulsifying agents can be classified according to: 1) Chemical structure: Synthetic Emulsifying Agents (Sodium stearate, Benzalkonium chloride). Natural Emulsifying Agents (Acacia, Tragacanth, Gelatin) Finely Dispersed Solids (Bentonite, Veegum) Auxilary Agents 2) Mechanism of action: Monomolecular Multi-molecular Solid particle films.

HLB Value

• The hydrophilic-lipophilic balance of a surfactant is a measure of the degree to which it is hydrophilic or lipophilic.

• Has an arbitrary scale of 1 - 18.• Low HLB Indicates? Low number of hydrophilic groups on the Molecule thus

imparting Lipophilic character. E.g. Spans have low HLB numbers.

• High HLB indicates? Emulsifier has a large number of hydrophilic groups on the

molecule thus imparting hydrophilic Character. E.g. Tweens have higher HLB numbers

Theories Of Emulsification

• Electric double layer theory.• Phase volume theory.• Hydration theory of emulsions.• Adsorbed film and interfacial tension theory.

Figure: Electric Double Layer

Figure: Interfacial Tension Theory

Figure: Surface Tension

Methods Of Preparation Of Emulsion

1) Dry Gum Methods2) Wet Gum Methods 3) Bottle Method 4) Beaker Method. 5) In situ Soap Method.

Instability