摘要 采用核磁共振氟谱(19 F quantitative nuclear magnetic resonance,19 F qNMR)结合氧弹燃烧的前处理方法对茶叶中总氟进行定量分析。19F qNMR法以氟离子δ=-119处信号特征为定性峰,以三氟乙酸δ=-75处信号特征为内标峰,采用氧弹燃烧的方式将茶叶样品中含氟物质转化为无机态氟,加入柠檬酸钠—乙二胺四乙酸二钠混合金属螯合剂以消除干扰,测定茶叶中氟离子的绝对含量。方法的最低检测浓度为2.0μg/mL。质控样品测定结果满意,实际样品加标回收率为96.3%~107.0%,方法重复性、精密度良好。利用氧弹燃烧19F qNMR法测定茶叶中总氟含量,30 min内能完成样品测试,有效减少样品分析时间,测定结果准确可靠。 Quantitative analysis of total fluorine in tea was established by using 19F quantitative nuclear magnetic resonance combined with the pretreatment method of oxygen bomb combustion.The 19F qNMR method used the signal characteristic of fluoride ion atδ=-119 as the qualitative peak and the signal characteristic of trifluoroacetic acid atδ=-75 as the internal standard peak.The fluorine-containing substances in tea sample was burned by oxygen bomb and converted into inorganic fluorine.Mixed metal chelating agent which included sodium citrate and disodium EDTA was added to eliminate interference and then the absolute content of fluoride ion in tea was determined.The minimum detection concentration of the method is 2.0μg/mL.The results of the quality control samples were satisfactory.The recovery rate of the actual samples were 96.3%~107.0%and the method repeatability and precision were good.The sample test can be completed within 30 minutes which effectively reduces the analysis time and the measurement result is accurate and reliable by using the method to determine the total fluorine content in tea.
出处 《食品与机械》 北大核心 2021年第4期58-62,共5页 Food and Machinery
基金 国家重点研发计划资助项目(编号:2018YFC1602304)。
关键词 定量核磁共振 内标法 茶叶 氟 氧弹燃烧 螯合剂 quantitative nuclear magnetic resonance internal standard method tea fluorine oxygen bomb combustion chelating agent
