Barfoed's test

Barfoed'sche the sample is a method to distinguish monosaccharide ( simple sugar ) such as glucose, galactose, mannose, fructose, di-, oligo-or polysaccharides. This evidence was found in 1873 by Danish chemist Christian Thomsen Barfoed.

In this method, the Barfoed'sche reagent, a mixture of dissolved copper acetate, sodium acetate and acetic acid, treated with solutions of the sugar to be tested and is heated for a few minutes in the water bath. If it is at the given sample is a monosaccharide, quick to form a reddish tint and red-brown copper (I ) oxide ( Cu2O ), which by reduction of copper ( II) ions of Barfoed solution in a weakly acidic environment as precipitation fails. Disaccharides react only after prolonged boiling, allowing the distinction.

Reaction equation

The detection reaction is similar to the Fehling test, however, under acidic conditions. The aldehyde function of an aldose is oxidized to the acid copper of oxidation state II is reduced to the oxidation state I: