title: Detection of exogenous citric acid in fruit juices by stable isotope ratio analysis.
abstract: 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.
authors.affiliation: EUROFINS, Rue Pierre Adolphe Bobierre, BP 42301, Nantes, France. ericjamin@eurofins.com
authors.forename: Eric
authors.initials: E
authors.lastname: Jamin
authors.forename: Frédérique
authors.initials: F
authors.lastname: Martin
authors.forename: Rebeca
authors.initials: R
authors.lastname: Santamaria-Fernandez
authors.forename: Michèle
authors.initials: M
authors.lastname: Lees
mesh_terms: D001628:Beverages / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis; D019343:Citric Acid / Q000032:analysis*; D003903:Deuterium / Q000032:analysis; D005506:Food Contamination / Q000032:analysis; D005638:Fruit / Q000737:chemistry*; D007554:Isotopes / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D002247:Carbon Isotopes; D007554:Isotopes; D019343:Citric Acid; D003903:Deuterium