崇明老白酒酿造贮存过程中氨基甲酸乙酯变化及检测方法优化

优化氨基甲酸乙酯（ethyl carbamate，EC）的气相色谱-质谱联用检测方法，跟踪崇明老白酒在酿造、加工及贮存过程中EC含量的变化，为控制米酒中EC的产生提供依据。样品前处理的最佳参数为：加入内标物EC后，调节pH值至9.0，分别加入3 次10 mL二氯甲烷作为直接萃取剂。在检测范围5～400 μg/L内呈良好线性关系，相关系数大于0.999，检出限为2 μg/L，定量限为5 μg/L。当添加水平分别为0.1、0.2、0.3 μg时，平均回收率为90.0%～97.5%，相对标准偏差为1.040%～2.778%。老白酒酿造过程中EC含量的增长缓慢，在煎酒灭菌后增长快速；常温条件下贮存样品的EC增长速率明显高于4 ℃条件下贮存样品，老白酒在室温条件下贮存1 a后EC含量为99.2 μg/L，低于蒸馏酒、清酒的最高限量。高温和长时间贮存会促进EC的产生，在老白酒生产流通环节中有必要优化灭菌条件，改善贮存条件。

Change in Ethyl Carbamate Content during Fermentation and Storage of Chongming Rice Wine and Sample Pretreatment Optimization for Ethyl Carbamate (EC) Detection

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.