Sulfite analysis of fruits and vegetables by high-performace liquid chromatography (HPLC) with ultraviolet spectrophotometric detection

Free and total sulfite were analyzed in acidified vegetable products, instant mashed potatoes, and dried apples. Sulfite was separated by HPLC and quantified with a UV-vis detector. Resolution from components of food samples was achieved by varying the acid concentration of the eluant solution and by appropriate choice of the analytical wavelength. The minimum detectable levels for sulfite were 0.5 mg/L for a 10-cm analytical column and 1.5 mg/L for a 30-cm column. For analyses done with a 30-cm column, the coefficient of variation was <2% for analysis of free sulfite and total sulfite in acidified vegetables. For dried apples and instant potatoes, it ranged from 1 to 6.5%. The corresponding analytical errors were <4% and 1.2-5.6%, respectively, for the 10-cm column.