What compounds other than a naphthol can be used as a reagent for the test?

A solution of naphthol in ethanol (95%) is known as Molisch reagent. It's also known as the purple ring test. Other than the Molisch reagent, concentrated sulfuric acid is also used in the test.A solution of naphthol in ethanol (95%) is known as Molisch

Molisch

Molisch's test is a sensitive chemical test, named after Austrian botanist Hans Molisch, for the presence of carbohydrates, based on the dehydration of the carbohydrate by sulfuric acid or hydrochloric acid to produce an aldehyde, which condenses with two molecules of a phenol (usually α-naphthol, though other phenols ...

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reagent. It's also known as the purple ring test. Other than the Molisch reagent, concentrated sulfuric acid is also used in the test.

What are the reagents are used in Molisch test?

Molisch's test involves the addition of Molisch's reagent (a solution of ∝- naphthol in ethanol) to the analyte and the subsequent addition of a few drops of concentrated H2SO4 (sulphuric acid) to the mixture.

Which of the following reagent is used for detection of alpha naphthol?

Procedure. The test solution is combined with a small amount of Molisch's reagent (α-naphthol dissolved in ethanol) in a test tube. After mixing, a small amount of concentrated sulfuric acid is slowly added down the sides of the sloping test-tube, without mixing, to form a layer.

Which chemical is used for carbohydrate test?

Molisch's test is a general test for carbohydrates. This test is given by almost all of the carbohydrates. In this test, concentrated sulfuric acid converts the given carbohydrate into furfural or its derivatives, which react with α-naphthol to form a purple coloured product. The chemical reaction is given below.

What is anthrone reagent test?

Anthrone test is a group test for carbohydrates that provides a rapid and convenient method for quantification of carbohydrates that are either free or bound to any lipids or proteins.

22 related questions found

How do you make 0.2 anthrone reagent?

Use 100ml conc. H2S04 in 40ml distilled H20. Cool with ice and add 0.2g anthrone. Use 0.1g of glucose in 100 ml H20 to make stock solution.

Does glucose give Molisch test?

Molisch is used to detect sugars such as glucose, fructose, mannose, and many more. Molisch test can be performed to detect all sorts of sugars such as monosaccharides, disaccharides, trisaccharides, and polysaccharides. So, if you want to test any sugar-free product, you may perform the Molisch test.

What reagent is used for protein testing?

The presence of protein is tested by the Biuret test for proteins. The Biurette reagent made of sodium hydroxide and copper (II) sulphate helps in determining the presence of protein in a sample.

How can we test carbohydrate?

1. Qualitative Tests for Carbohydrates.
2. α-naphthol solution is unstable and should be prepared fresh. Conc. H₂SO₄ should be along the sides of the test tubes causing minimal disturbance to the contents in the tube. 2) ANTHRONE TEST.
3. 5) SELIWANOFF'S TEST.
4. 6) Fehling's Test.
5. 7) Benedict's test.
6. 8) Picric acid test.
7. 9) Bial's test.

What kind of compound is alpha-naphthol?

1-Naphthol, or α-naphthol, is a fluorescent organic compound with the formula C10H7OH. It is a white solid. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on the naphthalene ring.

Why alpha-naphthol is used in VP test?

Alpha-naphthol acts as a color enhancer, but the color change to red can occur without it. Procedure: First, add the alpha-naphthol; then, add the potassium hydroxide. A reversal in the order of the reagents being added may result in a weak-positive or false-negative reaction.

Does lactose give Molisch test?

Solution: Lactose, glucose and fructose gives positive Molisch's test.

Does protein give Molisch test?

Molisch test is a group test for all carbohydrates, either free or bound to proteins or lipids. It is a sensitive test that requires precision for the detection of carbohydrates.

Why we use H2SO4 in Molisch test?

Principle of Molisch's test:

H2SO4 get dehydrated to form furfural and its derivatives. When monosaccharide are treated with conc H2SO4 or conc HCl, -OH group of sugar are removed in the form of water and furfural is formed from pentose sugar and hydroxymethyl furfural is formed from hexose sugar.

What group of substances give positive result with Molisch test?

Shows positive test for: All carbohydrates. Monosaccharides give a rapid positive test.

Does galactose give a positive iodine test?

Lactose and galactose give negative results with the fermentation test. When iodine (I2) is added to amylose, the helical shape of the unbranched polysaccharide traps iodine molecules, producing a deep blue-black complex. Amylopectin, cellulose, and glycogen react with iodine to give red to brown colors.

What are the protein tests?

Albumin and globulin are two types of protein in your body. The total protein test measures the total amount albumin and globulin in your body. It's used as part of your routine health checkup. It may also be used if you have unexpected weight loss, fatigue, or the symptoms of a kidney or liver disease.

What test can be used to differentiate fructose and galactose?

Barfoed's Test

It is a differentiating test to distinguish between monosaccharides and disaccharides. Barfoed's test is also based on the reducing ability of sugar.

How can biuret solution be used to test for proteins?

Biuret Test Procedure

1. Take 3 clean and dry test tubes.
2. Add 1-2 ml of the test solution, egg albumin, and deionized water in the respective test tubes.
3. Add 1-2 ml of Biuret reagent to all the test tubes.
4. Shake well and allow the mixtures to stand for 5 minutes.
5. Observe for any color change.

How can Biuret reagent detect protein compound?

The biuret method is based on the fact that proteins (and, as a rule, all substances containing two or more peptidic bonds) react with copper to form a colored complex whose absorption (λmax=454nm), in the presence of excess copper, is proportional to the amount of protein present.

Why purple ring is formed in Molisch test?

All carbohydrates (monosaccharides, disaccharides, and polysaccharides) pass the Molisch test. It is based on Sulphuric acid dehydrating the carbohydrate to produce an aldehyde, which condenses with two molecules of -naphthol, resulting in the appearance of a purple ring at the interface.

Can Seliwanoff's test be used to distinguish sucrose from fructose?

Seliwanoff's test is a chemical test which distinguishes between aldose and ketose sugars. A mixture of concentrated HCl and resorcinol of 3ml is added to the sugar. Then the solution is boiled for little time. If it is a ketose sugar like fructose and sucrose is the solution turns cherry red .

What happens in Fehling's test?

Principle of Fehling's Test

On heating, the sample with the Fehling's solution, bistartarocuprate (II) complex oxidizes the aldoses to corresponding aldonic acids. In the process, the copper (II) ions of the complex are reduced to insoluble yellow or red-colored precipitate or cuprous (I) oxide (Cu₂O) ions.

What carbohydrates are specifically extracted using 80% ethanol?

Mono- and oligosaccharides are soluble in 80% ethanol and almost all polysaccharides and proteins are insoluble in hot 8-% ethanol. Mono- oligosaccharides, most polysaccharides and most proteins are soluble in water. Therefore, the extraction with 80% ethanol is rather specific for removing mono- and oligosacchraides.