通过稳定同位素比率分析检测果汁中的外源柠檬酸
Detection of exogenous citric acid in fruit juices by stable isotope ratio analysis.
作者信息
Jamin Eric, Martin Frédérique, Santamaria-Fernandez Rebeca, Lees Michèle
机构信息
EUROFINS, Rue Pierre Adolphe Bobierre, BP 42301, Nantes, France.
出版信息
J Agric Food Chem. 2005 Jun 29;53(13):5130-3. doi: 10.1021/jf050400b.
A new method has been developed for measuring the D/H ratio of the nonexchangeable sites of citric acid by isotope ratio mass spectrometry (IRMS). Pure citric acid is transformed into its calcium salt and subsequently analyzed by pyrolysis-IRMS. The citric acid isolated from authentic fruit juices (citrus, pineapple, and red fruits) systematically shows higher D/H values than its nonfruit counterpart produced by fermentation of various sugar sources. The discrimination obtained with this simplified method is similar to that obtained previously by applying site specific isotopic fractionation-nuclear magnetic resonance (SNIF-NMR) to an ester derivative of citric acid. The combination of carbon 13 and deuterium measurements of extracted citric acid is proposed as a routine method for an optimum detection of exogenous citric acid in all kinds of fruit juices.
已开发出一种通过同位素比率质谱法（IRMS）测量柠檬酸非交换位点D/H比率的新方法。将纯柠檬酸转化为其钙盐，随后通过热解-IRMS进行分析。从正宗果汁（柑橘、菠萝和红色水果）中分离出的柠檬酸，与由各种糖源发酵产生的非水果来源的柠檬酸相比，系统地显示出更高的D/H值。用这种简化方法获得的同位素分馏与先前通过将位点特异性同位素分馏-核磁共振（SNIF-NMR）应用于柠檬酸酯衍生物所获得的结果相似。建议将提取的柠檬酸的碳13和氘测量相结合，作为常规方法，以最佳检测各类果汁中的外源柠檬酸。
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