苏冰霞+叶海辉+邓爱妮

摘要采用氢化物发生原子荧光法测定海南白沙绿茶和红茶中的硒含量，研究了仪器条件和还原剂等对硒原子荧光强度的影响。结果表明，最佳仪器条件为光电倍增管负高压300 V，灯电流80 mA；还原剂浓度为1.5%，载流盐酸浓度5%。该方法线性范围0～10 μg/L时，与荧光值线性关系好，回归方程为y=75.949x-8.795 4，相关系数r=0.999 8。方法检出限是0.024 μg/kg，测定标准物质中硒的回收率为97.7%～109.6%。以国家标准物质茶叶(GBW10016)为监控样品，标准物质茶叶测定值与标准值吻合。白沙绿茶和红茶硒元素含量分别是34.4和20.1 μg/kg。该方法线性范围宽、灵敏度高、检出限低，可用于茶叶等样品中硒元素含量的准确测定。

关键词原子荧光 ；白沙绿茶 ；白沙红茶 ；硒

分类号TS272.7

Optimized Determination of Selesium in Baisha Green and Red Tea

SU BingxiaYE HaihuiDENG Aini

(Center of Analysis and Testing / Hainan Provincial Key Laboratory of Quality and Safety for Tropical Fruits and Vegetables, CATAS, Haikou, Hainan 571101, China)

AbstractIn this study the content of selenium in Baisha green and red tea were determined by hydride generation atomic fluorescence spectrometry. The influence factor such as instrument conditions and the concentration of reducing agent were considered. The results showed that the best instrument conditions were the photomultiplier negative pressure 300V, lamp current 80mA; the concentration of reducing agent 1.5%, the concentration of hydrochloric acid current carrying 5%. The fluorescence values were good in the method when the linear range was 0 ~ 10μg/L, regression equation was y=75.949x-8.795 4, correlation coefficient, r=0.999 8, the detection limit was 0.024 μg/kg，and the recovery of method was 97.7% ~ 109.6%. This method was verified by analyzing the national reference material (GBW10016) and the found value was in good agreement with the certified value. The content of selenium in Baisha green and red tea was 0.0772 μg/kg and 0.0456 μg/kg. The method has wide linear range, high sensitivity, low detection limit, which was very suitable for the determination of trace selenium of tea in general laboratory.

Keywordshydride generation-atomic fluorescence spectrometry ;Baisha green tea ;Baisha red tea ; selesium

白沙绿茶和红茶为海南省五指山区白沙黎族自治县境内的国营白沙农场特产，中国国家地理标志产品。因海南中部适宜的气候与白沙陨石坑地区独特的土壤条件，品质优良，营养成分高。其中对白沙绿茶的检测分析证明白沙绿茶含有氨基酸、酶类、芳香特质、多酚类和生物碱等各种对人体有益的物质，成茶水浸出物为43.2%，水溶性灰分为71.4%。两项指标大大超过国家标准的34%和45%的指标。

硒是对人体有益的微量元素，有抗氧化、抗肿瘤、延缓衰老、提高免疫和解毒等生物与生理功能[1-2]。人体自身不能合成硒，只能从食物中适量摄取。补硒过量又会引起生物体中毒，世界卫生组织(WHO)、联合国粮农组织(FAO)、国际原子能机构(IAEA)均规定了明确指标：膳食硒的供给量为50～250 μg/d，成人个体硒最高安全摄入量为400 μg/d[3]。……