Emulsion: Identification tests : Pharmaceutics Notes PDF Books
The final preparation of both emulsions (o/w or w/o) looks the same in appearance with naked eyes, therefore certain tests are required to differentiate between them.
- Miscibility Test
- Staining Test
- Electrical Conductivity Test
- Fluorescence Test
- Cobalt Chloride Test
- This test is important to know the solubility of the continuous phase of the emulsion. For example- In O/W emulsion, a dilution test is done to know it’s diluted with water or not.
In this test the emulsion is diluted either with oil or water.
- O/W : Stable if Diluted with water, Unstable if Diluted with Oil
- W/O : Stable if Diluted with Oil, Unstable if Diluted with Water
- This test is important to know, which is a good conductor of electricity to find out the continuous phase. For example- In O/W emulsion, water is a continuous phase. Because water is a good conductor of electricity than oil.
Dye Solubility test
- This test is done by mixing the emulsion with water or an oil-soluble dye, and checked under a microscope to know which is in a continuous phase or dispersed phase.
The emulsion is mixed with a water-soluble dye (amaranth) and observed under the microscope.
O/W: Continuous phase appears red
W/O: If the scattered globules appear red and continuous phase colourless
- Oils have the property of fluorescence under UV light, while water doesn’t. Therefore, O/W emulsion shows a spotty pattern while W/O emulsion fluoresces.
Cobalt Chloride Test
- When a filter paper soaked in cobalt chloride solution is dipped in to an emulsion and dried
- O/W : blue to pink
- W/O : remains same
- As humidity increases, cobalt chloride changes colour from sky blue to purple to pink
Biphasic Liquids: Suspension: Definition, advantages, and disadvantages, Classifications, Preparation of suspensions, Flocculated and Deflocculated suspension Emulsions: Definition, Advantages & Disadvantages, Classification, Emulsifying agent, Test for the identification of the type of Emulsion, Methods of preparation, Stability of emulsion
First Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise