Question

Dunstan’s test is used for identification of:
A) Glycerol
B) Acetone
C) Glycol
D) Ethanol

Answer 1

Hint: It is the test which is performed by the use of the chemical i.e. acts as a pH indicator and gives pink colour for basic solution. The substrate on which this test is performed is the simple polyol compound which is found in lipids. It is having various food industries and medicinal use.

Complete answer:
Dunstan’s test is the test used for the detection of glycerol. When phenolphthalein drops are added in borax then the solution turns pink in color. When glycerol is added to this solution, the solution turns colorless on cooling. When the solution is heated then the color again reappears. This is the principle of Dunstan’s test.

The correct option is A i.e. glycerol.

Additional Information: There is another test also called a acrolein test in which glycerol is heated with $KHSO_4$ that produced a very offensive odor due to the formation of acrolein. Its aqueous solution is responsible for reducing fehling’s solution and tollen’s reagent.
Glycerol is the polyol compound used as a moisturizing agent in cosmetics, foods and drugs. It is also a component of fats and oils. It is colorless, odorless, viscous liquid having a sweet taste and is non-toxic in nature.
Due to the presence of three hydroxyl groups, it is miscible in water and showing the hygroscopic behavior.

Note: Applications of glycerol are:
It is used as an effective marker to measure liver disease.
It is used as a sweetener in the food industry.
It is used as an anti freezing substance for automotive applications in colder countries.
It is used as a humectant in the meat processing industries.
Due to its antibiotic and antiviral properties it is widely used in FDA approved wound and burn treatment.