Folin & Wu’s Phosphate, Molybdate Solution is used for determination of blood sugar by Folin Wu's method.Glucose and other reducing substances under alkaline conditions reduce the cupric ions of the copper reagent to cuprous ions.Cuprous oxides reacts with phosphomolybdic acid to from molybdenum blue. Intensity of molybdenum blue is directly proportional to the reducing sugars present. It is measured at 420 nm and compared with a known standard.