Tests for Carbohydrates Flashcards
A general test for carbohydrates and reacts with H2SO4 to yield a purple condensation product
Molisch test
Carbohydrates react with concentrated H2SO4 to form furfural which reacts to give a bluish green colored complex. It is used for the detection of carbs in blood serum, milk and others.
Anthrone test
A test for reducing sugars. Reacts with NaOH and turns into yellow, orange then dark brown with the odor of caramel
Moore’s test
A test for reducing sugars. The cupric ion present in an alkaline reaction medium is reduced to cuprous ion and forms cuprous oxide (brick red) precipitate and is more sensitive than Benedict’s test
Fehling’s test
A test for reducing sugars. Like in Fehling’s test, sugars with a free aldehyde or ketone group reduce cupric hydroxide in alkaline solution to red (or red orange) colored cuprous oxide
Benedict’s test
A test for reducing sugars. The silver diamine complex is reduced by the presence of free functional groups in the sugars to metallic silver
Tollen’s test
It is used to distinguish reducing monosaccharides from reducing disaccharides
Barfoed’s test
A test for reducing sugars. In alkaline medium, glucose and fructose reduce Bi(OH)3 formed from bismuth subnitrate into black metallic forming leaving a black precipitate
Nylander’s test
Reducing sugars form characteristic osazone crystals when heated with an excess phenylhydrazine. The positive result is yellow to pale orange osazones
Phenylhydrazine test
Test for pentoses. In the presence of concentrated HCl, pentoses form a five member ring known as furfural. The positive result is a blue-green solution
Bial’s Orcinol test
