Barfoed's test

Barfoed's Test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate. (Disaccharides may also react, but the reaction is much slower.) The aldehyde groupe of the monosaccharide which normally form a cyclic hemiacetal is oxidized to the carboxylate  A number of other substances, including sodium chloride, may interfere.

It is primarily used in botany.

The test is similar to the reaction of Fehling's solution to aldehydes.