砖茶氟浸出的试验研究

Study on Leaching of Fluoride in Brick-tea

[目的]探讨影响砖茶氟浸出的因子。[方法]利用氟离子选择电极法，研究不同的茶水比[1：（25～200）]、浸提次数、浸提时间（5～60min）、TISAB中柠檬酸钠的浓度（60、180、240g）、茶叶粒度（过20、40、60目）等条件对砖茶氟浸出的影响。[结果]茶水比越小，砖茶氟浸出量越高；第一泡茶汤的氟浸出量最高，占6泡总浸出量的72．5％，第2泡茶汤次之，占总浸出量的17．2％；低浓度的柠檬酸钠对砖茶样品中干扰离子的掩蔽效果较差，以浓度为120g／L时的测定效果好；氟的浸出率随着浸提时间的延长而增加，一般在30min时趋于稳定；茶叶粒度越小，越有利于茶氟的浸出。[结论]茶水比、浸提次数、浸提时间、粒度、TISAB中柠檬酸钠的浓度等因素均对茶氟的浸出有明显影响。

[ Objective ] The study aimed to discuss the factors of affecting the leaching of fluoride in brick-tea. [ Method] The ion specific electrode methodology was used to study the effects of different ratio of tea and water（ 1：25 -200） ,infusing times,infusing time（5 -60 min） ,sodium citrate concn, in TISAB （60, 180,240 g） and tea size （20, 40, 60 sieve size） etc. on leaching of fluoride in brick-tea. [Result] The smaller the ratio of tea and water was, the higher the leaching amount of fluoride in brick-tea was ; the fluorine leaching amount in the first infusion was very high, accounting for 72.5% of total amount of 6 infusions, and that in the second infusion was next, accounting for 17.2% of total infusion amount; the sodium citrate at low concn, had poor masking effect on the interferingion in the brick-tea sample and the sodium citrate at 120 g/L had good determination effect ; the leaching rate of fluoride was increased along with the prolonging of infusing time and was constant at 30 min in general; the smaller tea size was more propitious to the leaching of fluoride in brick-tea. [ Conclusion ] The factors such as the ratio of tea and water,infusing times,infusing time,tea size and sodium citrate concn, in TISAB showed obvious effects on the leaching of fluoride in brick-tea.