Emulsion suitable for intravenous injection Balm Water in
Emulsion suitable for intravenous injection. Balm: Water in oil emulsion Dodecane droplets in a continuous phase of water/glycerol mixture. Emulsions Sodas: Oil in Water emulsion Mayonnaise: Oil in Water emulsion Milk: Oil in Water emulsion
Outline • • Introduction Types of emulsions Emulsifying agents Tests for emulsion types Emulsion Stability Phase Inversion, Creaming Emulsion Breaking
Introduction Emulsion – Suspension of liquid droplets (dispersed phase) of certain size within a second immiscible liquid (continuous phase). Classification of emulsions - Based on dispersed phase Oil in Water (O/W): Oil droplets dispersed in water Water in Oil (W/O): Water droplets dispersed in oil
Emulsions encountered in everyday life! Pesticide Asphalt Skin cream Ice cream Metal cutting oils Margarine Stability of emulsions may be engineered to vary from seconds to years depending on application
Emulsifying Agents Stable suspensions of liquids constituting the dispersed phase, in an immiscible liquid constituting the continuous phase is brought about using emulsifying agents such as surfactants.
W/O vs. O/W emulsions Bancroft's rule Emulsion type depends more on the nature of the emulsifying agent than on the relative proportions of oil or water present or the methodology of preparing emulsion. The phase in which an emulsifier is more soluble constitutes the continuous phase In O/W emulsions – emulsifying agents are more soluble in water than in oil. In W/O emulsions – emulsifying agents are more soluble in oil than in water.
1) Size distribution of droplets Emulsion with a fairly uniform size distribution is more stable than with the same average droplet size but having a wider size distribution 2) Phase volume ratio As volume of dispersed phase stability of emulsion (eventually phase inversion can occur) 3) Temperature , usually emulsion stability
General Guidelines 1. Some General Ratios of Emulsions 1. 2. 3. 2. Vinaigrette = 3: 1 oil to vinegar Mayonnaise = 6: 1 oil per egg yolk Hollandaise = 3: 1 clarified butter per yolk There are three types of emulsions: stable, semipermanent and unstable. To create a stable emulsion an emulsifying agent must be added. 3. 1. Most common emulsifier is Lecithin (found in egg yolks, garlic, mustard)
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