Molisch Test- Definition, Principle, Procedure, Result, Uses


Carbohydrates are one of the most abundant and important biomolecules in nature. They have various roles in living organisms, such as providing energy, storing glucose, forming structural components, and participating in signaling pathways. Carbohydrates can be classified into different types based on their size and complexity, such as monosaccharides, disaccharides, oligosaccharides, and polysaccharides.

To detect the presence of carbohydrates in a given sample, various chemical tests can be performed. One of the most common and simple tests is the Molisch test, which is a group test for all carbohydrates. This means that the test can identify any type of carbohydrate in a sample, but it cannot distinguish between different types of carbohydrates. The test is named after the Austrian botanist Hans Molisch, who first described it in 1897.

The Molisch test is based on the reaction of carbohydrates with a specific reagent called Molisch reagent, which consists of α-naphthol dissolved in ethanol. The reagent reacts with the carbohydrates to form a purple or violet colored complex at the interface of the acid and test layer. The acid used in the test is usually concentrated sulphuric acid, which catalyzes the dehydration of sugars to form furfural or hydroxymethylfurfural. These aldehydes then condense with two molecules of naphthol to form the colored complex.

The Molisch test is a quick and easy way to confirm the presence of carbohydrates in a sample. However, it has some limitations and drawbacks, such as its lack of specificity, sensitivity, and interference by other substances. Therefore, it is often followed by other tests that can identify the specific type of carbohydrate present in the sample. Some examples of these tests are Benedict`s test, Barfoed`s test, Seliwanoff`s test, Bial`s test, and Iodine test.

In this article, we will explain the principle, procedure, result, uses, and limitations of the Molisch test in detail. We will also provide some examples of how the test can be applied to different samples and situations. We hope that this article will help you understand the basics and applications of the Molisch test as a group test for all carbohydrates.