Abstract:

An optimized gas chromatography-mass spectrometry (GC-MS) method for the quantification of ethyl carbamate
(EC) was presented to monitor the changes in EC content in Chongming rice wine during fermentation, sterilization and
storage. Optimal parameters for sample preparation were obtained as follows: adjusting the pH to 9.0 following addition
of the internal standard and afterwards adding 10 mL of methylene chloride in three portions as an extraction solvent. The
method showed a good linearity (R2 > 0.999) over the concentration range of 5 to 400μg/L. The limit of detection (LOD)was 2 μg/L, and the limit of quantification (LOQ) was 5 μg/L. At spiked levels of 0.1, 0.2 and 0.3 μg, the recoveries were in
the range from 90.0% to 97.5%,with relative standard deviations (RSDs) ranging from 1.040% to 2.778%. EC was increased
slowly during fermentation and rapidly after sterilization. The growth rate of EC in the wine stored at room temperature was
significantly higher than that of the sample stored at 4 ℃. The results showed that EC content reached 99.2 μg/L when the
rice wine was stored at room temperature for 1 year, which was lower than the maximum limit for distilled spirits and sake.
High temperature and long-term storage increased the formation of EC. It is necessary to optimize the sterilization conditions
and to improve storage conditions.

Key words: Chongming rice wine, gas chromatography-mass spectrometry, ethyl carbamate, determination, optimization, change