The aldehyde group of the monosaccharide which normally forms a cyclic hemiacetal is oxidized to the carboxylate.

A number of other substances, including sodium chloride,[3] may interfere.

Its author is the Danish chemist Christen Thomsen Barfoed[1] and it is primarily used in botany.

[citation needed] The test is similar to the reaction of Fehling's solution to aldehydes.

[5] 1 drops of Barfoed's reagent is added to 2 mL of given sample in a test tube and boiled for 3 minutes and then allowed to cool.