Estimation of reducing sugar by using dinitro salicylic acid method

The approach is based on the detection of the existence of a free carbonyl CO group of reducing sugars. In an alkaline media, the ketonic and aldehyde functional groups of fructose and glucose are first oxidized by 3, 5-dinitrosalicylic acid (yellow hue) to 3-amino-5-nitrosalicylic acid (orange-red).