咖啡因具有中樞神經興奮作用，廣泛存在於植物及一般飲料中，本研究利用靈敏 的事效液相層析法進行咖啡因的含量分離。 以 0.1M 硼酸鈉緩衝液 (pH6.4) 一甲醇 (72: 28,v/v) 為移動相，使用 C-18 的分離管柱; 流速為每分鐘 1ml 進行分離， 並以紫外光檢 測器偵測，波長設在 270nm。咖啡因的偵測極限是 10ng/ml。分析結果頗示，在飲料產品中 ， 以咖啡 A 的咖啡因含量最高 (503.58 ± 1.28ug/ml); 在茶葉與咖啡產品中，咖啡中咖 啡因約含量 (39.8 ± 0.3mg/g) 較茶葉高。

　　　　　Caffeine was found in a number of plants and beverages, the content of caffeine was determined us- ing a sensitive high-performance liquid chromatographic method. The separation was achieved on a liq- uid chromatographic reversed-phase 5C18 column with a mobile phase of 0.1 M sodium borate buffer (pH 6.4)-methanol (72:28, v/v) at a flow rate of 1 mL/min. The eluted caffeine was detected with 270 nm. The limit of detection of caffeine was 10 ng/mL. These results suggested among the beverages, the coffee had the greatest caffeine content (503.58 ± 1.28 Ug/mL), and among tea and coffee products, cof- fee had greater caffeine content (39.8 ± 0.3 mg/g).