Properties of Carbohydrates

Molisch test

Test for the presence of carbohydrates with the exceptions of tetrose and triose.

Fehling’s test

Test for reducing sugar using a Cu2+ complex to produce a red precipitate.

Nylander’s test

Test for reducing sugar and is also used to test sugar in urine.

Benedict’s test

Test for reducing sugar (amount of reducing sugar)

Moore’s test

Test for reducing sugar wherein the solution is heated with Alkali (NaOH)

Bial’s Orcinol test

Test for pentose and hexose

Seliwanoff’s test

Test for ketose

Barfoed’s test

Test to distinguish monosaccharides from disaccharids

Molisch’s reagent

a-naphthol in ethanol and drops of H2SO4

Fehling’s solution

Cu2+ complex

Nylander’s solution

Bismuth subnitrate

Benedict’s solution

Sodium carbonate, sodium citrate, and copper (II) sulfate

Moore’s test

Produces a yellow to brown color with caramel-like smell

Molisch test results 

Produces a purple ring in almost all carbohydrates

Nylander’s test results

Produces a black precipitate

Benedict’s test results

Blue to brick red color depending on the amount of reducing sugar in a solution.

Orcinol reagent

Concentrated HCl and FeCl2

Pentose

Bluish or green color

Hexose

Muddy brown/yellow/gray color

Seliwanoff’s reagent

Resorcinol in concentrated HCl

Ketose

Deep cherry-red or burgundy in 1-2 minutes

Aldose

Faint pink/yellow in 10 or more minutes

Barfoed’s reagent

Copper (II) acetate in dilute acetic acid solution

Monosaccharide

Brick red precipitate