茶叶氟化物提取方法对比与电位法测定条件优化

Comparison of extraction methods and potentiometric determination of fluoride in tea

对比茶叶氟化物提取方法,并对氟化物电位法测定条件进行优化。结果表明,不同提取方法对茶叶氟化物提取效率表现为水浴法(93.17%)>酸振荡提取(68.19%)>超声提取法(62.38%)。选用电位法测定茶叶氟化物线性范围在30～200 mg.kg-1之间,平均回收率为90.48%,相关系数R2为0.992 2,方法LOQ和LOD分别为54 mg.kg-1和18 mg.kg-1。采用此法分析了安徽省4种茶叶氟化物含量在52.26～73.80 mg.kg-1之间,低于农业部茶叶氟含量安全限量标准(≤200 mg.kg-1)。该研究结果为茶叶中氟化物含量的快速测定与茶叶质量安全性评价提供参考。

The different methods for extracting fluoride from tea were compared, and the potentiometric method for determining fluoride in tea liquid was optimized. The results showed that the recoveries with the boiling water extraction method （93.17 %） were higher than those with the shaking extraction in acidic water （68.19 %） and the ultrasonic extraction （62.38 %）. In this paper, the linear range of potentiometric determination of fluoride in tea was between 30 and 200 mg.kg^-1, and the mean recovery was 90.48 % with the square of the correlation coefficient （R2） of 0.992 2. The limit of quantification （LOQ） and limit of detection （LOD） were 54 mg.kg^-1 and 18 mg·kg^-1, respectively. The fluoride contents in four tea samples from Anhui province were ranged from 52.26 mg·kg^-1 to 73.80 mg·kg^-1, and the fluoride components in spring tea were lower than that in autumn tea, and both of them were lower than that of the national standard of fluoride in tea （200 mg.kg^-1）. The results provide reliable methods for rapid determination and quality assessment of fluoride in tea.