超声波萃取-离子选择电极法测定茶叶中氟含量

[目的]利用超声波萃取-离子选择电极法对贵州省部分地区茶叶中氟含量进行测定。[方法]采用超声波萃取-氟离子选择电极法,对贵州省部分地区6种茶叶的全叶、粉末及浸出物中氟含量进行测定,研究不同浸泡次数、浸泡温度、浸泡时间对其中3种茶叶氟浸出率的影响。[结果]贵州省不同地区所选茶叶样品中的氟含量为46.24～121.77 mg/kg,未超过我国农业行业标准;浸出物中氟含量随超声时间的增加而上升,且在超声30 min时浸出率最大;茶叶的粒度大小对氟离子的提取没有显著的影响;随着浸泡次数的增加,茶水中的氟浓度依次降低;茶叶中氟的浸出率随着浸泡温度和浸泡时间的增加而升高。[结论]应尽量避免大量饮用含氟量高的茶叶,并避免长时间的冲泡以防止茶叶中的氟过度溶出。

Determination on Fluoride Content in Tea by Ultrasonic Extraction and Ion-selective Electrode Method

[Objective] The study aimed to determine the fluorine content in the tea from the part areas of Guizhou Province by using the ultrasonic extraction and ion-selective electrode method.[Method] The fluorine content in the whole leaf,tea powder and the extract in 6 kinds of tea in the part area of Guizhou Province were measured by using the ultrasonic extraction and ion-selective electrode method and the effects of different soaking times,soaking temperature and soaking time on the fluorine leaching rate in 3 of 6 kinds of tea were studied.[Result] The fluorine contents in the selected tea samples in different area of Guizhou Province were 46.24-121.77 mg/kg,which didn’t exceed the agriculture industry standard in China.The fluorine content in the extract was increased with the increment of the ultrasonic time and the leaching rate of the fluorine was greatest when the ultrasonic extraction time was 30 min.The size of tea had no obvious effect on the extraction of the fluorine ion.The fluorine concn.was decreased orderly with the increment of the soaking times and the leaching rate of the fluorine was enhanced with the increment of soaking temperature and soaking time.[Conclusion] It shouldn’t drink a lot of the tea with high-fluorine content as possible as one can,at same time,it should avoid making tea for long time so as to prevent the excessive dissolution of the fluorine in the tea.