市售飲料中咖啡因含量檢驗方法之探討與調查

DETERMINATION AND INVESTIGATION OF CAFFEINE CONTENT IN BEVERAGE

本計劃除探討液相層析法分析咖啡因之可行性外，並利用高效液相層析測定法及中國國家標準分光光度測定法，同時分析市售飲料中咖啡因之含量，以比較兩者之差異。經檢體添加咖啡因5、10、15、20、30ppm五種濃度之回收試驗結果比較顯示：分光光度測定法於波長276.5nm檢測咖啡因，易受具有相同吸光光譜之成份干擾，使實驗數值產生誤差，其回收率為98.6～127.3%，變異係數為5.1～20.8%。而以高效液相層析法檢測時，其回收率為92.8～95.8%，變異係數為1.5～2.8%，且無干擾情形，較分光光度法更適於檢驗基質複雜之食品，以避免檢驗結果之誤差。本計劃於八十年七月至八十一年五月，共計抽驗飲料檢體150件，檢出含咖啡因者計87件，檢出率為58%，各類飲料之檢出含量均符合現行用量標準。檢出含咖啡因之檢體，除1件未按規定標示於外包裝上，其餘檢體均符合現行飲料咖啡因標示管理規定。

Caffeine in beverages were assayed by both the Spectrophotometer and HPLC to determine whether the HPLC method is a suitable substitute for spectrophotometric method. Recovery studies were performed at 5, 10, 15, 20, 30 ppm fortifcation levels in one of the sample. The results of recoveries by spectrophotometer were between 98.6～127.3%. Although the method was, sensitive enough, however, the problem of interferring impurities can not be overcome. The coefficient of variation by Spectrophtometer were between 5.1～20.8%. Without interferring impurities problem, the recoveries of HPLC were 92.8～95.8% and coefficint of variation were between 1.5''' 2.8%. 150 samples of beverage were purchased from Taiwan markets. The result revealed that 87 out 150 samples (58%) contained caffeine and meet the hygenic standard. Only one of the sample which contained caffeine was not labelled with name of caffeine.