Molisch's Test - Qualitative Test in Carbohydrates

Overview

Molisch's test is a test for carbohydrates in general. This test is useful for identifying any compound which can be dehydrated to furfural or hydroxymethyl furfural in the presence of H2SO4. The lesson will demonstrate the procedure in the Molisch's Test.

 

It also describes the laboratory instruments and materials that are used in such tests. The objective of the test is to describe the basis of qualitative tests for monosaccharides, disaccharides and polysaccharides and use the test to distinguish specific sugars form each other.

Author(s): George KoffuorView Details of Author
Year: 2012
Keywords: molisch test, carbohydrates, qualitative test, furfurals
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cc-by-nc© 2012, KNUST

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Introduction

 

Molisch's test is a test for carbohydrates or compounds which can be dehydrated to furfural or furfural derivatives in the presence of the concentrated sulphuric acid (H2SO4).  Furfural is derived from the dehydration and rearrangement of pentoses and pentosans while hydroxymethyl is produced from hexoses and hexosans. The α-naphthol reacts with the cyclic aldehydes to form purple coloured condensation products.

 

Although this test will detect compounds other than carbohydrates (i.e.) glycoproteins, a negative result indicates the absence of carbohydrates.

 

Objectives

 

Describe the Molisch's Test and the biochemical basis of the test.

Distinguish between specific sugars from each other.

 

Lesson Content

 

Molisch's Test (video)
Molisch's Test

 

Credits

 

Author

gkoff

Dr. George Koffuor
Department of Pharmacology
College of Health Sciences - KNUST
Kumasi, Ghana

Student Volunteer


Manasseh Amenyedokui
Department of Communication Design
CASS - KNUST
Kumasi, Ghana

 

OER Technical Support

 

 

 

Benjamin Prempeh
OER Media Specialist
KNUST, Kumasi - Ghana
adobrog@yahoo.com

John Kofi Dogbey
Media Specialist
KNUST,Kumasi - Ghana
johndogbey@gmail.com


Voice Over

ella kasanga

Ella Kasanga
Kumasi, Ghana

 

Acknowledgment

 

This programme was produced with support from the following:

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