Determination of Free and Total Sulfite in Red Globe Grape by Ion Chromatography

Abstract

Sulfiting agents have been used wide-spread for prolonging shelf life of berries, excessive of sulfur dioxide would cause food allergies to humans. Conventional methods mainly focus on the determination of free or total sulfite in liquid samples, and are not suitable to analyze berries with low level of sulfite. Here formaldehyde method and ion chromatography were coupled to determine the residues of the free and total sulfites in Red Globe grape. Both standard calibration curves showed good correlation between anion peak area and concentration. To free and total sulfite, limits of detection were 0.002 and 0.05 mg/L and recoveries ranged from 88 – 93% and 87 – 98%, respectively. Relative standard deviation values of repeatability and intraday precision for standard anions with the same sample were less than 3%. The method developed was well applicable to be used to determine free and total sulfite in barriers, especially to those with color.