超声萃取-离子综合测试仪法测定茶叶中氟含量

Determination of fluoride content in tea by ultrasonic extraction and a comprehensive ion testing instrument

目的：建立超声萃取-离子综合测试仪测定茶叶中氟的方法。方法：茶叶样品采用盐酸（1＋1,v/v）为萃取剂经超声提取20 m in后,加氟离子强度缓冲液,用离子综合测试仪直接测定。结果：该方法的回收率在92.0%-108.0%之间,相对标准偏差0.58%-1.92%,测定茶叶标准物质GBW 07065的氟含量,其结果与参考值进行t检验,二者无显著性差异。结论：本法具有精密度高,准确度好,操作简便实用的优点,值得推广。

Objective：To develop an assay for the direct determination of fluoride content in tea by ultrasonic extraction and a comprehensive ion testing instrument. Methods：After ultrasonic extraction of tea with hydrochloric acid （ 1 ＋ 1, v/v） for 20 minutes, pre - added the buffer solution of fluoride ion strength, the fluoride concentration was directly measured by the comprehensive ion testing instrument. Results：The recovery of this method was in the range of 92.0% to 108.0%, the relative standard deviations were between 0. 58% -1.92%. In addition, in order to compare the accuracy with the GB/T5009.18 -2003 method, four tea samples with different concentrations were determined by both methods. It showed that the average results of the two methods had no significant differences by T -test which t value （t = 1.87 ） was less than to.952. 23. Furthermore, determined the tea standard materials GBW07065, it also showed that the average value by the developed method had no significant difference with the reference value by T- test which t value （t = 1.87 ） was less than to. 952. 23. Conclusion：The method has the advantages of high precision and good accuracy, and it is simple and practical, and worth promoting.