紫外光谱法测定饮料中的咖啡因含量

建立了一种测定饮料中咖啡因含量的紫外光谱分析法.采用三氯甲烷为萃取剂,控制三氯甲烷与饮料的体积比为8:1,经充分振荡后离心分离,取清液在276 nm处测定紫外吸收光谱,能够满意地测定市售饮料中的咖啡因浓度.分析结果的相对标准偏差小于4%;在饮料中加入不同浓度的咖啡因标准溶液,回收率在94.0%～112.0%之间.

Determination of caffeine in beverages by ultraviolet spectrophotometry

An ultraviolet（UV） spectrophotometric method was established to determine the content of caffeine in beverage.Thus chloroform was used as the extraction agent to mixed with beverage at a volume ratio of 8∶1.Resultant mixture was sufficiently oscillated and centrifugally separated to give the supernatant for UV detection at a wavelength of 276 nm.In this way the content of caffeine in beverages on markets was satisfactorily determined at a relative standard deviation of less than 4%.When standard caffeine was introduced into six kinds of beverages on markets at different concentrations,the recovery is 94.0%-112.0%.