超声波萃取-离子选择电极法测定茶叶中的氟含量

Study of the Fluoride Content in Tea by Ultrasonic Extraction and Ion-Selective Electrode Method

采用100℃的去离子水冲泡茶叶，以超声波萃取-离子选择电极法测定茶叶中氟含量的方法进行试验，结果表明；该测定方法的回收率在97．5％～103．0％之间，标准偏差小于2．0％；超声波萃取法检测到的氟含量普遍高于国标法，后者与前者之比在49．zN～59．1％之间；在超声波处理茶叶时，茶叶的粒度大小对氟离子的萃取没有显著的影响，茶全叶和碾碎、过40目筛的茶叶末检测出的氟含量比较接近，两者相差在5％左右。用该方法测定国家一级标准物质茶样的氟含量与其标准值相符。因此，超声波提取方法具有较高的准确性和可靠性，是测定茶叶中氟离子的一个新的萃取方法。

The fluoride content in tea was determined by ultrasonic extraction and ion-selective electrode method. The results showed that the rate of recovery rangeed from 97. 5%-103. 0% the standard deviation was less than 2%. The test results of ultrasonic extraction are more than national standard method, the ratios of national standard method to ultrasonic extraction method are from 49.2%- 59.1%. The effect is small with the size of tea; the test result of the crushed tea is about 5% higher than that of the whole tea. The test result of national reference substance of tea sample （GBW07605 （GSV-4）） showed no difference from the data of the standard by ultrasonic extraction method.