The behaviour of leached aluminium in tea infusions

The behavior of leached aluminium (Al) was studied using GF-AAS with different sample pretreatments and RP-HPLC with lumogallion as the precolumn reagent. The results showed that Al species in tea infusion could be categorized into three groups: large organic compounds, small stable organic compounds and free form Al. The compositions of Al species in a tea infusion would vary with the method of the tea production. For non-fermented teas such as Long-Jin and Moli-Hua, most of the leached Al in the first tea infusion was in large organic compounds and small stable organic compounds, and free form Al consisting of less than 10%. In the case of semi-fermented and fully fermented teas such as Shuihsien and Pu-Erh, the main compositions of Al species in the first infusion were free form Al and small stable organic compounds, while Al in large organic compounds made up about 14% and 4%, respectively. When 1-g tea leaves were infused with 100 ml boiling water, about 21% Al in the tea leaves was leached into the water in the first infusion and a total of about 27% of the Al in the tea leaves was leached into the water in four infusions.