Molisch’s Test, Principle and other Facts

In the vast field of science, there are many tests that are used to check the presence of carbohydrates but the simplest, easiest and most successful of them is Molisch’s test. Here in this article, you’re going to learn things such as 1. What is the Molisch test? 2. The principle of Molischs Test. 3. Molisch Reagent and 4. Procedure and Precautions for this test. I tried my best to write this in simplest of words so that people even with weak English can understand it better and have a better grasp over their study.

What is Molisch’s Test?

Molish test is a delicate synthetic test for the checking of present carbohydrates, in light of the lack of hydration of the sugar by sulfuric acid or hydrochloric acid to deliver an aldehyde, which consolidates with two particles of phenol bringing about a red-or purple-hued compound. This test was named after a Botanist from Austria Hans Molisch. This test is considered as a very easy to understand test for a student of all levels and that’s why it is the most used. Molisch’s test works on a simple principle which is explained elaborately in the next heading.

Principle of Molisch’s Test:

To detect the presence of carbohydrates, the solution is first treated with a strong acid.This is for hydrolyzing the carbohydrate to monosaccharide. A compound named furfurol is then made when water is removed from monosaccharides. This furfurol is consolidated to shape a violet ring or other shaded compound.The compound furfurol is dense with alpha-naphthol or other phenol present in molisch’s reagent.

Molisch’s Reagent:

In every chemical test, it is necessary that you must prepare a reagent. Reagent much is compatible and right according to the needs of the test. Here to perform Molischs Test our reagent will be a-naphthol which is dissolved in ethanol and this is used in the test tube. This is the best reagent that could be prepared for the test and is completely compatible with the test. Once prepared this can be further used in the procedure of checking the presence of Carbohydrates in a solution with the help of Molisch’s test.

Procedure involved in Molisch’s Test:

To do Molisch’s test there is not very complex procedure involved. In fact, you can do it easily if you have basic chemistry knowledge and also basic knowledge of all the equipment involved in the procedure. Just follow this simple guide and you can easily find the presence of carbohydrates with the help of Molisch’s test.

1. First, you will need to gather some equipment involved in the process. First thing is to take a good test tube and a pipette. Once you have these two, you can continue with the procedure.
2. Now in the test tube, insert 5 ml solution. Make sure that you do this with the help of pipette and IU have already told you to arrange it. If you put it directly, you might do some mistake in the quantity of the solution.
3. Take the reagent which you using and two or three drops of it in the solution. Don’t exceed the amount from two to three drops because it might affect the test and you won’t get good results.
4. Once if you have added the drops of reagent, mix it gently by shaking or moving the test tube around. Do the mixing for quite some time till it gets mixed completely.
5. Now you will need to add little drops of any of the strong minerals acids such as hydrochloric acid or Sulphuric acid. Make sure that when you add these, make sure that you hold the test tube inclined. Now you are done with the test but what was the result?
6. You will know the results are positive or there are carbohydrates present in the by the formation of the violet reddish ring formed at the carbohydrate and acid meeting point.

Note: Don’t perform the test before you have taken care of few very important things. But what are those thing? That is what you’re going to know in the next heading.

Precaution before performing Molisch’s test:

Here is a list of some very important precautions that you need to take before and while performing the Molisch’s test.

1. This is the most important precaution because the whole test depends on it. Always make sure that you have measured the solution before using it in the test because the quantity of this solution is everything and it directly effects the results of the test.
2. 2nd this is also a very important one. When you add the acid that you have chosen for the solution, make sure that it is not being added directly. Means that you add the acid in the test tube from the sideways or you can say by dropping it down the wall of the test tube. This won’t cause the acid to react quickly and your whole procedure will remain smooth and simple.
3. Do not pour down all the acid at once. Make sure that you add the acid slowly and in drop by drop order. Pouring it down could cause the sudden reaction and your whole procedure could be lost.
4. Few drops of Molisch reagent are enough to serve the purpose. Adding too much is not a very good idea since a reagent could prove harmful when added in more quantity.
5. Never ever shake the reddish violet ring once it is formed. Shaking the ring destroys all your work and you will have to go through the whole procedure again.
6. The acid that is being used in this procedure is a strong acid and is very dangerous for skin. So when you are adding the acid, pour it gently. Wearing skin protective gloves are also very crucial but if you don’t have them, you can rely on pouring the acid gently.

Result of Molisch Test:

Once you’ve followed the whole procedure carefully along with taken precautions there are almost 100% chances that your result will be positive. It should be a reddish violet ring formed at the point where acid and carbohydrates are meeting.

Final Words:

So this was all from the Molisch’s test to test the presence of carbohydrates in a solution. Did this help you? Please leave us your feedback and keep visiting our blogs.