Benedict's test for sugars. Image 1 of 3. Water baths with two test tubes containing glucose and Benedict's solution. The water bath on the right is warmer and the colour change is faster. Benedict's reagent (light blue) consists of a solution of copper (II) sulphate (CuSO4), tartaric acid and sodium hydroxide. It is used to detect sugars such as glucose, giving the orange colour seen towards the end of this sequence. This is a precipitate that forms as the copper sulphate is reduced to insoluble orange copper (I) oxide. Not all sugars give the positive result (sucrose does not). For the sequence, see C015/0443 to C015/0445.