Determination of reducing sugar in vegetables by Potassium Ferricyanide- iron(III) chloride color system

Potassium Ferricyanide is produced by reducing reaction of potassium ferricyanide by reducing sugar, then it reacts with iron(III) chloride to obtain Prussian blue, whose intensity is the linear with content of reducing sugar. The optimum conditions for color reaction were investigated, and the results shows that it exhibits good linear relationship within 0.8-4μg/ml, molar absorption coefficient is 3.4 × 10⁴ L/(molcm), and relative standard deviation is 1.18%-4.84%, recovery ratio is 99.61-100.34%. The method features simple, quick and the availability of instrument, and the results are satisfactory in the determination of reducing sugar in vegetable.