Determination of sulfur dioxide in food by liquid chromatography with pre-column derivatization

A derivatization method to determine the sulfur dioxide content in food was established. Under weakly acidic conditions, fluorescent 2H-isoindole-1-sulfonate was synthesized by a derivatization reaction using an ammonium salt and o-phthalaldehyde as the derivative reagent. High-performance liquid chromatography and a highsensitivity fluorescence detector were used for detection, in which a fluorescence spectrophotometer was used to determine the maximum excitation wavelength and emission wavelength of2H-isoindole-1-sulfonate. When the excitation wavelength was 323 nm and the emission wavelength was 386 nm, the linear range of fluorescence intensity of the sulfur dioxide standard was 0-10 mu g/mL, and the correlation coefficient was 0.996. The standard recoveries of six kinds of food were approximately 80-110%, the RSD was 0.2-2.89, the detection limit was 0.2 mg/kg, and the quantitative limit was 0.7 mg/kg. The results of this research indicate that this method is suitable for determining sulfur dioxide in food.