Identification test for emulsion: The Following tests are used to distinguish between o/w and who emulsions.
Table of Contents
1. Dilusion Test
The emulsion is diluted with water. In case the emulsion remains stable after its dilution it is o/w emulsion. The w/o emulsion breakdown on the addition of water, but is stable on the addition of oil.
2. Dye Test
- The Scarlet red dye is mixed with the emulsion.
- Place a drop of the emulsion on a microscopic slide. cover it with a cover slip and examine it under a microscope.
- If the disperse globules appear red and the “ground” colorless the emulsion is o/w type.
- The reverse condition occurs in w/o type emulsion i.e. the dispersed globules appear, colorless in the red ground.
3. Conductivity Test
- Water a good conductor of electricity, whereas oil is a non-conductor of electricity.
- It can be performed by dipping a pair of electrodes, connected through a low-voltage bulb in the emulsion.
- If the bulb glows on passing the electric current.
- The emulsion is o/w type because the water is in the continuous phase.
- In case of the bulb does not glow, the emulsion is w/o type because oil is in the continuous phase.
4. Fluorescence Test
- Certain fixed oils possess the physical properties of fluorescing in the presence of ultraviolet radiation. On microscopic observation of emulsion under u.v. radiation the fluorescence indicates.
- Oil is present in the continuous phase [w/o type emulsions] and droplet fluorescence indicates that oil is present in the dispense phase [o/w type emulsion].
Also, read: Classification of Emulsifying agents