Seliwanoff’s Test: Principle, Reagent Preparation, Procedure And Results Interpretation

What Is Seliwanoff’s Test?

Seliwanoff’s test is a chemical test which differentiates between Aldose and ketose sugars. If the sugar contains a ketone group, it is a ketose whereas if it contains an aldehyde group, it is an Aldose. This test is much like Bial’s test; it relies on the principle that, when heated, ketoses are more rapidly dehydrated than Aldoses. It is named after the Russian chemist Theodor Seliwanoff who devised the test in 1887.


  • The main objective of Seliwanoff’s test is to distinguish between sugars that have a ketone group (ketose) and sugars that have an aldehyde group (Aldoses).

Principle Of Seliwanoff’s Test

Seliwanoff’s test is particularly useful in the field of organic chemistry and biochemistry for the identification and differentiation of sugars.

Seliwanoff’s test is specific to ketonic saccharides (fructose or sucrose).To differentiate between aldehydic and ketonic saccharides, a ketose is heated with a strong mineral acid. When concentrated hydrochloric acid is added to a sample containing ketose sugar, ketoses undergo dehydration to yield furfural derivatives more rapidly than Aldoses. These derivatives (dehydrated ketose) then react with equivalents of resorcinol in a series of condensation reactions to produce complexes with a deep cherry red color. The test reagent causes the dehydration of ketohexoses to form 5-hydroxylmethylfurfural, which then reacts with resorcinol present in the test reagent to produce a red product within two minutes. Aldohexoses reacts so more slowly to produce a faint pink color. Fructose and sucrose are two common sugars which give a positive test. Sucrose gives a positive test as it is a disaccharide consisting of fructose and glucose.  


Reagent And Material Required

  • Test tube(s)
  • The carbohydrate solution to be tested
  • Resorcinol solution
  • Concentrated hydrochloric acid (HCl)
  • Water bath or heating source
  • Test tube holder or tongs
  • Safety goggles and lab coat (for safety)


Prepare the Test Solutions:

  • Ensure you have a small amount of the carbohydrate solution you want to test. If the carbohydrate is a solid, dissolve it in a small amount of water to create a solution.
  • If you don’t have a resorcinol solution ready, prepare it by dissolving resorcinol in water or alcohol to make a 2-3% solution. It should be colorless.

Label the Test Tubes:

  • If you’re testing multiple carbohydrates, label the test tubes to keep track of your samples.

Add Reagents to the Test Tube:

  • Take a test tube and add your carbohydrate solution to it.
  • To the same test tube, add a few drops of resorcinol solution. The resorcinol should completely cover the carbohydrate solution.

Acidify the Mixture:

  • Carefully add a few drops of concentrated hydrochloric acid (HCl) to the test tube. Be cautious, as concentrated HCl is corrosive and should be handled with care.

Heat the Test Tube:

  • Hold the test tube with a test tube holder or tongs.
  • Heat the test tube gently by immersing it in a boiling water bath or heating it over a Bunsen burner flame. Heat it for a few minutes.

Observe and Record:

  • Pay attention to any color changes that occur in the test tube during heating.
  • If the carbohydrate is a ketose (ketone sugar), it will produce a red color.
  • If the carbohydrate is an aldose (aldehyde sugar), it will not produce a significant color change, and the solution may remain colorless or turn slightly yellow due to caramelization.

Clean Up:

  • Dispose of the test tube contents properly, following laboratory safety guidelines for chemical waste disposal.
  • Rinse the test tube thoroughly with water.

Seliwanoff’s Test Result Interpretation

  • Positive Test: The solution changes to cherry red-color within the first 2 minutes of heating. This indicates that the sample contains ketoses.
  • Negative Result:  The color of solution remains unchanged or absence of cherry red color after prolonged period of heating. This indicates that the test sample does not contain ketoses.

Limitation Of Seliwanoff’s Test

  • Seliwanoff’s test can distinguish between aldoses and ketoses but does not provide information about the specific sugar involved. It doesn’t identify the exact type or structure of the sugar present in the sample.
  • The test may produce false positives or false negatives under certain conditions. For example, some compounds other than sugars can react with resorcinol and HCl to produce a red color, leading to a false positive result. Conversely, some sugars may not react as expected due to their structural characteristics, leading to false negatives.
  • Seliwanoff’s test cannot differentiate between isomeric sugars. Isomers are molecules with the same molecular formula but different structural arrangements. Since the test relies on a general reaction with ketones or aldehydes, sugars with similar functional groups will give similar results.
  • When heated, some sugars may undergo caramelization, which can produce a yellow or brown color, leading to difficulty in interpreting the results. Caramelization is a chemical reaction that breaks down sugars into other compounds, and it can interfere with the test’s accuracy.
  • Seliwanoff’s test is primarily used for the differentiation of aldoses and ketoses. It is not suitable for the identification of other types of carbohydrates or for distinguishing between different aldoses or ketoses. Additional tests and analytical techniques are often needed to further characterize and identify specific sugars.