Comparison of Methods for determining Sulfur Dioxide in Food by Distillation Titration
Nitrogen-filled distillation-acid-base titration and Kjeldahl nitrogen determination instrument water vapor distillation-iodometry were used to determine the sulfur dioxide content in dried shiitake mushrooms,dried longan and wine,respectively,and the methodologies were compared.The results showed that the recoveries,precision and accuracy of the two methods for measuring dried longan and wine met the standard requirements,and there was no significant difference.The recoveries of dried shiitake mushrooms at the spiked levels of 50 mg·kg-1 and 200 mg·kg-1 by the Kjeldahl nitrogen determination instrument water vapor distillation-iodometry were 176.0%and 134.0%,respectively,which were not in accordance with the standard requirements,and therefore not suitable for the detection of sulfur dioxide in shiitake mushrooms.Compared with the Kjeldahl nitrogen determination instrument water vapor distillation-iodometry,the nitrogen-filled distillation-acid-base titration method has a wider range of applications and higher accuracy,but the operation is complex and time-consuming.
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