[Determination of exogenous sulfur dioxide in Shiitake mushroom based on gas liquid separation combined with ion...

Based on the characteristics of exogenous sulfur dioxide in Shiitake mushroom, a gas-liquid separation pre-treatment device combined with ion chromatography was applied to determine the residual amount of exogenous sulfur dioxide in food while eliminating the endogenous and other interference substances.

The acidic reaction solution and the testing samples were mixed in a gas-liquid separation device. The exogenous components contained in the sample were extracted by the air flow under acidic conditions and oxidized into sulfuric acid before being analyzed using the ion chromatography. The exogenous sulfur dioxide content in the mushroom sample was thus illustrated by measuring the sulfate concentration in the absorption solution using ion chromatography coupled with Metrosup A Supp 5-150(4 mm×150 mm) anion chromatography column.

When using 0.5 mol/L hydrochloric acid to react with the sample during gas-liquid separation for 10 minutes at an air flow rate of 0.1 L/min, and using 1.0% hydrogen peroxide as the absorbing solution, the linear relationship of sulfur dioxide concentration was good in the range of 0.605 mg/L to 30.2 mg/L, r=0.9993. The limit of detection of this method was 0.176 mg/L, and the limit of quantification was 0.528 mg/L. Low, medium, and high concentration levels of spiked recovery were performed on lilium brownii and dried shiitake mushrooms. The recovery rate of dried lilies ranged from 89.0% to 97.4%, with a relative standard deviation of 2.79% to 3.23%. The recovery rate of dried shiitake mushrooms was 90.4% to 97.5%, with a relative standard deviation of 2.53% to 3.16%(n=6).

This pretreatment method can effectively eliminate the influence of endogenous substances carried by Shiitake mushroom and other foods and interfering substances in other foods on the measurement result. The experiment device is simple, easy to operate, fast, relatively sensitive and accurate, and is applicable for the detection of sulfur dioxide content in domestic and foreign food samples.