Determination of caffeine content in commercial beverages by HPLC and electrochemical methods

• Main Authors: Jing-Jhao Lan, 藍景昭
• Other Authors: Hsi-Pin Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/84305733412862485077

碩士 === 元培科技大學 === 食品科學研究所 === 101 === To ensure that caffeine content of packaged and unpackaged beverages comply with their food labeling requirements, this study was to investigate the caffeine content of 91 commercially packaged beverages including 41 coffee drinks, 39 tea drinks, 11 energy drinks, and 23 unpackaged drinks including 8 coffee drinks and 15 tea drinks using the high performance liquid chromatography (HPLC) method in accordance with the Chinese National Standard inspection (CNS)-9432, as compared with the electrochemical method during the period of April to November, 2012. The results showed that the caffeine content of packaged coffee, tea and energy drinks ranged from 116 to 863 ppm, 0 to 264 ppm and 0 to 595 ppm, respectively, and the caffeine content of unpackaged coffee and tea drinks ranged from 360 to 1293 ppm and 154 to 333 ppm, respectively. The caffeine content in 10 packaged coffee drinks, 1 tea drink and 2 energy drinks were found exceed 10 % of their caffeine content labeling in which one coffee drink exceeded 106 % labeled caffeine content. The caffeine contents in commercially packaged coffee drinks were similar to that of unpackaged coffee drinks whereas the caffeine contents in commercially unpackaged tea drinks were more than that of packaged tea drinks. In addition, the electrochemical method based on Cyclic voltammetry with Gold-nanostructured screen-printed electrode was used to detect the caffeine content of those drinks above and compared the accuracy to the HPLC method. The electrochemical method showed above 92 % relative percentage as compared to the HPLC method. The electrochemical detection could be an alternative method for determining the caffeine content. The parameters of the detection conditions may be required to revise in order to improve the accuracy and sensitivity of the method in the further study.