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

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.