Rapid furfural test

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The rapid furfural test is a chemical test used to distinguish between glucose and fructose. The rapid furfural test is similar to Molisch's test but uses concentrated hydrochloric acid instead of concentrated sulfuric acid and the solution is boiled. [1] Dilute sugar solution is added to ethanolic 1-naphthol and concentrated hydrochloric acid. The solution is then boiled and if a purple colour forms within thirty seconds, fructose is present. If a purple colour does not appear before thirty seconds, glucose is present. [2]

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H
22
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11
.

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Hydroxymethylfurfural (HMF), also known as 5-(hydroxymethyl)furfural, is an organic compound formed by the dehydration of reducing sugars. It is a white low-melting solid which is highly soluble in both water and organic solvents. The molecule consists of a furan ring, containing both aldehyde and alcohol functional groups.

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<span class="mw-page-title-main">Hydrochloric acid</span> Aqueous solution of hydrogen chloride

Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical.

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The murexide test is an analytical technique to identify the presence of caffeine and other purine derivatives in a sample. These compounds do not respond to the common alkaloid identification tests such as Dragendorff's reagent. In this test, crude drugs are mixed with a tiny amount of potassium chlorate and a drop of hydrochloric acid. The sample is then evaporated to dryness and the resulting residue is exposed to ammonia vapour. Purine alkaloids produce a pinkish-purple color in this test due to formation of murexide, which the test is named after.

References

  1. O.P. Agarwal. Advances Practical Oraganic Chemistry. Krishna Prakashan Media. p. 42.
  2. Dandekar (1 January 2004). Practicals And Viva In Medical Biochemistry. Elsevier India. p. 18. ISBN   978-81-8147-025-6.