Quantitative Analysis of Reducing Sugars by 3, 5-Dinitrosalicylic Acid (DNSA Method)

The method is based on the detection of presence of free carbonyl C=O group of reducing sugars. Initially oxidation of the ketonic and aldehyde functional group of fructose and glucose, respectively, by 3, 5-Dinitrosalicylic acid (yellow color) to by 3-amino-5-nitrosalicylic acid (orange-red)∗ in alkaline medium.