Standardization of a colorimetric method for the determination of fructose using o-cresol: Sulphuric acid reagent.

Fructose developed a pinkish orange chromogen on treatment with o-cresol: 70% sulphuric acid at 32°C for 15 minutes with a λ max of 500nm. Fructose was 185 times more chromogenic than glucose. Total carbohydrate and fructose values in protein-free filtrate of normal serum samples were in the range, 55.4-86.3 mg/dl and 1.55-3.29 mg/dl, respectively. In diabetes, the observed values were 197-354 mg/dl and 2.91-6.81 mg/dl, respectively.