Simultaneous Determination of Soluble Total Sugar and Reducing Sugar in Food by FI-Spectrophotometry

It was found that the soluble total sugar in food was hydrolyzed to reducing sugar with 1 mol·L-1HCl solution, and a colored complex was formed by its reaction with p-hydroxybenzoic acid hydrazide, having its absorption maximum at the wavelength of 420 nm. Based on these facts, the determination of soluble total sugar and reducing sugar in food by flow injection (FI)-spectrophotometry was proposed. Linearity range was kept between 50.0 and 800 mg·L-1, with detection limits (3s) of 5.32 mg·L-1 (for reducing sugar) and 2.71 mg·L-1 (for soluble total sugar). The proposed method was used in the determination of soluble total sugar and reducing sugar in food, and values of recovery found were in the range of 98.0%-101% with RSD′s (n=6) in the range of 1.1%-1.5%.