11/22/2023 0 Comments Cobalt chloride paper test![]() ![]() Individual Soil & Plant Tissue Test Kits.Instruments for Water & Laboratory Analysis.If colorless droplets are visible on a colorless background, it indicates the emulsion type is W/O, or if red-colored droplets are visible on a colorless background, it indicates the emulsion type is O/W.ĭroplets of blue color observed against colorless backgrounds indicate that the emulsion is O/W, while droplets of colorless colors observed against colorless backgrounds indicate the emulsion is W/O. Observing the result of a small sample to be mounted on a compound microscope takes place in both cases. Test: Take a small amount of sample emulsion and mix it with either a water-soluble dye such as amaranth or an oil-soluble dye such as scarlet blue. Creaming downward indicates a water-based emulsion.ĭye test Soluble dyes make the color according to their phase of solubility, water-soluble dyes make the color according to the water phase while oil-soluble dyes make the color according to the oil phase.Whenever upward creaming is present, it indicates that the emulsion type is O/W.It is an o/w type if it shows only spotty fluorescence.įormation of creaming Testing: heating the sample emulsion in a suitable test tube for 10 minutes and observing the result In these cases, pink spots appear against a blue background, which indicates the type of emulsion.įlorescence testWhen an emulsion shows continuous fluorescence under a microscope after exposure to ultraviolet radiation, it is a w/o type.The blue cobalt chloride strip should become completely pink if it indicates O/W emulsion.Blue strips are soaked in sample emulsion for 5 minutes, then dried and the results are observed. Test: To carry out this test, a Whatman filter strip is impregnated with cobalt chloride solution for 10 minutes, and when the strip dries, it becomes blue. ![]() This shows that the emulsion is of the o/w type. A dye added to an oil emulsion (Scarlet red C or Sudan III) causes a red continuous phase, which indicates that the oil is not emulsified.Ĭobalt chloride testWhen filter paper is dipped in an emulsion and dried, its color turns pink when soaked in cobalt chloride solution. If neither of those occurs, it is without type. The scattered globules should appear red and the continuous phase should be clear. In the case of a red continuous phase, the emulsion is of the o/w type, which is the case since the external phase is filled with water and the dye will dissolve in it, creating the color. A glowing electric bulb occurs when the emulsion is of the o/w type.ĭue solubility testTests are conducted by mixing an emulsion with a water-soluble dye (amaranth) and observing the results under a microscope. An electric bulb is connected to a pair of electrodes that are dipped into the emulsion and a pair of electrodes are dipped into an emulsion. Since water is the external phase in the case of o/w emulsion, this will be a positive result. Water in oil emulsions can be diluted by adding an aqueous solvent, while oil in water emulsions can be diluted through an oily liquid.Ĭonductivity testSince water conducts electricity well, it can be used as a test medium. The emulsion, however, will break if it is diluted with oil since oil is incompatible with water. The emulsion will remain stable if the water is the dispersion medium and is diluted with water. A conclusion can only be reached after at least two tests have been completed.ĭilution test During this test, either oil or water is used to dilute the emulsion. Both final preparations (o/w and w/o) appear identical to the naked eye therefore, additional tests are needed to distinguish between them.
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