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    茶叶中29种挥发性有机物的固相微萃取-气相色谱-质谱法测定及其危害水平评估

    Determination of 29 Volatile Organic Compounds in Tea by Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry and Hazard Level Assessment

    • 摘要: 建立了固相微萃取-气相色谱-质谱法(SPME-GC-MS)测定茶叶中29种挥发性有机物(VOCs)含量的方法,并对随机选择的100个茶叶样品进行了危害水平评估。在顶空进样瓶中加入茶叶样品和内标物乙酸苯乙酯,采用纤维头DVB/CAR/PDMS在平衡温度60℃下吸附目标化合物30 min,解吸后不分流进样,以HP-FFAP色谱柱为固定相在程序升温条件下分离,分离得到的目标化合物进入配有电子轰击离子(EI)源的质谱仪,在选择离子监测(SIM)模式下进行测定,内标法定量。采用食品安全指数(IFS)评价茶叶中VOCs的危害水平。结果显示:29种VOCs的质量分数在0.05~0.50 mg·kg-1内和内标物的质量分数之比与两者对应的峰面积之比呈线性关系,检出限(3S/N)为0.001 6~0.031 6 mg·kg-1;对实际样品进行加标回收试验,所得回收率为74.4%~86.6%,测定值的相对标准偏差(n=6)为2.4%~8.9%;100份茶叶样品中均有VOCs的检出,VOCs总检出量为0.035~0.113 mg·kg-1,所得的IFS最大值为2.79×10-3,远低于1,说明茶叶中的VOCs对人体潜在危害水平是可以接受的。

       

      Abstract: A method was developed for determination of 29 VOCs in tea by SPME-GC-MS, and a hazard level assessment was conducted on randomly selected 100 tea samples. Tea sample together with internal standard of phenylethyl acetate was added in headspace vials, the target compounds were adsorbed by DVB/CAR/PDMS fiber tip at equilibrium temperature of 60℃ for 30 min, and then introduced in to GC-MS in splitless mode after desorption. HP-FFAP chromatographic column was used as stationary phase for separation under temperature programmed condition. The target compounds obtained entered a mass spectrometer equipped with EI source, and deteted in selective ion monitoring (SIM) mode with internal standard method for quantification. The hazardous level of VOCs in tea was evaluated by food safety index (IFS). The results showed that the ratios between the mass fraction of 29 VOCs in the range of 0.05-0.50 mg·kg-1 and those of internal standard were linearly related to the respective peak area ratios, with detection limits (3S/N) in the range of 0.001 6-0.031 6 mg·kg-1. Recovery test was made on the actual samples by standard addition method, giving results in the range of 74.4%-86.6%, and RSDs (n=6) of measured values ranged from 2.4% to 8.9%. VOCs were all detected in 100 tea samples with total content of VOCs detected in the range of 0.035-0.113 mg·kg-1, and value of maximum IFS (2.79×10-3) was far less than 1, indicating that the potential hazardous level of VOCs in tea was acceptable.

       

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