Luo Wenhong, Ang Catherina Y W, Gehring Theresa A, Heinze Thomas M, Lin Lawrence J, Mattia Antonia
U.S. Food and Drug Administration, National Center for Toxicological Research, Division of Chemistry, 3900 NCTR Rd, HFT-230, Jefferson, AR 72079-9501, USA.
J AOAC Int. 2003 Mar-Apr;86(2):202-8.
Analytical methodologies with ultrasonic extraction and liquid chromatography (LC) were developed for the determination of phenolic compounds in dietary supplements containing Echinacea. The phenolic compounds determined by these methods included caftaric acid, chlorogenic acid, cynarin, echinacoside, and cichoric acid. Samples from tablets, capsules, and bags of tea blends were extracted by sonication for < or = 30 min with methanol-water (60 + 40). The extracts were centrifuged and filtered, and the filtrates were diluted and analyzed by LC using a reversed-phase column and coulometric electrochemical (EC) detection. The mobile phase was acetonitrile-ammonium formate buffer, pH 3.5 (15.3 + 84.7) containing tetrabutyl ammonium hydrogen sulfate as an ion-pairing reagent. Extraction conditions (e.g., composition of the extraction solvent and sonication time) were optimized for different types of samples. Intra- and interday analytical variations were determined, and intraday analyses were performed by 2 independent analysts using 2 different LC systems. Results were generally comparable. The LC method with EC detection showed better sensitivity and selectivity when compared with LC with ultraviolet detection, although results were similar for the 2 methods for major compounds, i.e., caftaric acid, echinacoside, and cichoric acid. The identities of these major compounds found in samples were confirmed by LC/electrospray ionization mass spectrometry.
建立了采用超声提取和液相色谱（LC）测定含紫锥菊属植物的膳食补充剂中酚类化合物的分析方法。通过这些方法测定的酚类化合物包括咖啡酰酒石酸、绿原酸、洋蓟素、紫锥菊苷和菊苣酸。片剂、胶囊和混合茶包中的样品用甲醇 - 水（60 + 40）超声提取≤30分钟。提取物经离心和过滤，滤液稀释后用反相柱和库仑电化学（EC）检测的LC进行分析。流动相为含硫酸氢四丁铵作为离子对试剂的乙腈 - 甲酸铵缓冲液，pH 3.5（15.3 + 84.7）。针对不同类型的样品优化了提取条件（如提取溶剂的组成和超声时间）。测定了日内和日间分析变化，日内分析由2名独立分析人员使用2种不同的LC系统进行。结果总体可比。与紫外检测的LC相比，采用EC检测的LC方法显示出更好的灵敏度和选择性，尽管两种方法对主要化合物（即咖啡酰酒石酸、紫锥菊苷和菊苣酸）的结果相似。通过LC /电喷雾电离质谱法确认了样品中这些主要化合物的身份。
