Description
Fehling’s solution No. 1 is a chemical reagent used in analytical chemistry for the detection and quantification of reducing sugars, particularly aldoses such as glucose and fructose. It is composed of copper(II) sulfate (CuSO4) dissolved in water and tartaric acid. Fehling’s solution No. 1 is typically blue in color due to the presence of the copper(II) ions. When heated with a solution containing a reducing sugar, such as glucose, in the presence of an alkali (usually sodium hydroxide), the copper ions are reduced to copper(I), forming a brick-red precipitate of copper(I) oxide. This reaction is used in Fehling’s test to qualitatively determine the presence of reducing sugars in various substances.