ICP-AES法测定茶叶中的4种微量元素及其溶出特性的探究

Determination of 4 trace elements in tea by ICP-AES and discussion of their dissolution characteristics

为考查浸泡温度和浸泡时间对茶叶中铜、锌、锰、钡等矿物元素溶出量的影响,用微波消解处理茶叶样品,测定茶叶中4种元素的含量;分别用40℃、55℃、70℃、85℃、100℃的50ml蒸馏水冲泡茶叶20min,考查4种元素溶出量随温度的变化规律;采用相似的方法浸泡茶叶,12h后再测定4元素的含量,考查隔夜茶中4元素的含量随温度的变化规律。测定表明该品牌茶叶中含有较为丰富的铜、锌,而锰和钡的含量相对较低;温度在85～100℃时4种元素的溶出量较为稳定;放置12h的隔夜茶中,温度变化对4种元素的溶解量影响不大。该方法测定茶叶中的4种矿物元素含量,回收率在95.4%～104.5%,方法简单、快捷,并且同一样品处理液可同时测定多种矿物元素的含量,实验方案可靠,测定的数据可信。

In order to study the influences of steeping temperature and steeping time on the dissolution of 4 mineral elements（Cu, Zn, Mn and Ba） in a tea, the tea samples were treated by microwave digestion and the contents of these elements were determined. The tea was steeped in 50 ml distilled water of different temperatures（40, 55, 70, 85 and 100 ℃）, respectively, for 20 min, and the law of dissolution change with temperature was investigated. Then, the tea was steeped in the same way, and the contents of the 4 elements were determined 12 h later to investigate the law of content change with temperature overnight. The results showed that the tea contained relatively high Cu and Zn, but low Mn and Ba. Water of 85-100℃ little affected the dissolution of the 4 mineral elements, but water of 40-85℃ had a high effect on their dissolution 20 min later. Temperature had a low effect on the dissolution of the 4 mineral elements 12 h later. ICP-AES can be used to determine the contents of the 4 mineral elements in tea accurately with a recovery of 95.4% - 104.5%. It＇s simple and fast, and using this method, the contents of the 4 mineral elements can be determined in the same solution at the same time. The results provided a scientific theoretical basis for people to drink tea scientifically.