循环中子活化分析茶叶中的氟含量

Cyclic neutron activation analysis of fluorine concentration in Chinese teas

应用堆循环中子活化分析(Cyclic neutron activation analysis,CNAA)和三种传统氟测量方法分析了含氟标准参考物质茶叶(GBW10016)中氟含量。结果表明,CNAA具有准确性好、灵敏度高、省时、用量少、溯源性强、抗干扰性好等优势。CNAA分析四类16种商品茶中氟含量的结果显示,茶叶中氟含量依次为黑茶、红茶、乌龙茶、绿茶,其原因与茶叶的选料及加工工艺密切相关。个别黑茶氟含量高达276 mg/kg,超出国家限量标准(≤200 mg/kg),存在饮用安全风险。

Based on advantage of cyclic neutron activation of ^20F （t1/2=1 1.03 s）, cyclic neutron activation analysis （CNAA） and three traditional methods, i.e. UV-vis spectroscopy, fluorine ion selective electrode, and chromatography of ions, were used to determine fluorine concentration in standard reference materials of tea （GBW10016）. Compared with the three traditional methods, CNAA is accurate, sensitive, time-saving, little sample amount, strong traceability and good anti-interference. Fluorine concentrations in 16 commercial teas of four categories were determined by using CNAA. The results showed that fluorine concentrations of brick tea, black tea, oolong tea and green tea are 60-276, 54-66, 37-59 and 34-49 mg/kg, respectively. It was also found that the fluorine concentrations in different tea categories are likely attributed to their raw materials and production process. Fluoride concentration in one tea product was 276 mg/kg, while the national standard is ≤200 mg/kg.