顶空气相色谱-质谱法测定茶叶中溴甲烷  

Determination of methyl bromide residues in different kinds of tea by headspace gas chromatography-mass spectrometry

作　　者：罗春连 LUO Chunlian(Review Technology Center of Fujian Industrial Product Production License,Fuzhou 350003,China)

机构地区：[1]福建省工业产品生产许可证审查技术中心,福州350003

出　　处：《化学分析计量》2023年第7期30-34,共5页Chemical Analysis And Meterage

摘　　要：基于顶空气相色谱-质谱技术建立茶叶中溴甲烷含量的检测方法。样品处理条件:将茶叶样品研磨粉碎,过600μm筛,制备成茶粉。分别称取2.50 g茶粉于20 mL顶空瓶中,加入5 mL的饱和氯化钠溶液,立即旋盖密封,置于顶空装置中,于40℃保温30 min。采用DB-5MS石英毛细管柱(30 m×0.25 mm,0.25μm)作为气相色谱的分离柱,柱温为50℃,以100∶1的分流比进样,进样体积为100μL,载气(氦气)流量为0.80 mL/min。质谱采用电喷雾离子源(ESI),正离子模式,溴甲烷SIM监测离子为m/z 94。以4种不含溴甲烷的茶叶为空白基质对所建立的顶空气相色谱-质谱法进行方法学验证,溴甲烷的质量在0~400 ng范围内与色谱峰面积线性良好,检出限和定量限分别为0.006mg/kg和0.02 mg/kg,加标回收率为91.97%~105.33%,变异系数不大于10.77%(n=6)。该方法灵敏度和准确度高、重现性好,适用于茶叶中溴甲烷含量的分析检测。A method for detecting methyl bromide content in various types of tea was developed by using the headspace gas chromatography-mass spectrometry(GC-MS).The sample handling conditions:tea powder was prepared by grinding tea samples and sifting over 600μm.Weigh 2.50 g tea powder into 20 mL headspace bottle,add 5 mL saturated sodium chloride solution,seal immediately,place in the headspace device,and hold at 40℃for 30 min.A DB-5MS quartz capillary column(30 m×0.25 mm,0.25μm)was used as the separation column of gas chromatography,the column temperature was 50°C,the sample was injected with a split ratio of 100/1,the injection volume was 100μL,and the carrier gas(He)flow rate was 0.80 mL/min.Mass spectrometry was performed using electrospray ionization(ESI)in positive ion mode,and the ion monitored by methyl bromide SIM was m/z 94.Using 4 kinds of tea leaves without methyl bromide as blank matrices,the established headspace GC-MS method was validated.The mass of methyl bromide had good linearity with the chromatographic peak area in the range of 0-400 ng.Additionally,the detection limit and quantitative limit were 0.006 mg/kg and 0.02 mg/kg,respectively.The recoveries were between 91.97%and 105.33%,and the coefficients of variation were not more than 10.77%(n=6).This method is highly sensitive,accurate,and reproducible,making it ideal for determining the presence of methyl bromide in various types of tea.

关 键 词：顶空气相色谱-质谱法 茶叶 溴甲烷 

分 类 号：O657.7[理学—分析化学]