超声提取离子色谱法测定茶叶浸出液中的氟化物

目的]研究并优化茶叶的浸出方法,并在优化的浸出条件下采用离子色谱法测定茶叶浸出液中的氟含量。方法]优化了离子色谱测量茶叶浸出液中氟化物的浸出方法。在Ionpac AS9-HC分离柱上用9 mmol/L Na2CO3淋洗液做流动相进行洗脱并进行测定。结果]溶液中氟离子在0.02～5.00μg/g浓度范围内保持良好的线性关系,仪器检出限为1.5μg/L。试验方法对5种不同产地不同种类的茶叶回收率为97.62%～102.07%,精密度为1.01%～1.63%。安溪铁观音及云南普洱茶的氟化物含量比四川花茶和祁门红茶高,宜兴绿茶氟化物的含量最低,该法与国标氟离子选择电极法测量结果无显著性差异。试验研究的茶叶浸出液中氟含量均高于国家饮用水标准。结论]离子色谱法对茶叶浸出液中氟化物的测定具有较好的应用价值,建议人们适量饮茶。

Determination of Fluoride in Tea Extract with Ion Chromatography Method and Ultrasonic Extraction Process

Objective] To study the tea extraction process,and determine the fluoride content in tea extracts by ion chromatography under the optimized extraction conditions.Method] The ion chromatography determination conditions were optimized,the Ionpac AS9-HC anion separation column and an eluant of 9 mmol/L Na2CO3 were used for elution and determination.Result] The linear range of the calibration curve for fluoride was 0.02-5.00 μg/g with a detection limit of 1.5 μg/L.The recoveries were 97.62%-102.07% with RSD of 1.01%-1.63% in all teas.Content of fluoride in Tieguanyin and Pu-erh tea is higher than that in flower tea and black tea.Fluoride in green tea is the minimum.Results obtained by this method checked quite well with those obtained by standard method.In this work,content of fluoride in tea was all above the limited value recommended in GB,China.Conclusion] Chromatography method can be well used in determination of fluoride in tea extract,we suggest that people drink tea properly.