title: Is it really organic?--multi-isotopic analysis as a tool to discriminate between organic and conventional plants.
abstract: Novel procedures for analytical authentication of organic plant products are urgently needed. Here we present the first study encompassing stable isotopes of hydrogen, carbon, nitrogen, oxygen, magnesium and sulphur as well as compound-specific nitrogen and oxygen isotope analysis of nitrate for discrimination of organically and conventionally grown plants. The study was based on wheat, barley, faba bean and potato produced in rigorously controlled long-term field trials comprising 144 experimental plots. Nitrogen isotope analysis revealed the use of animal manure, but was unable to discriminate between plants that were fertilised with synthetic nitrogen fertilisers or green manures from atmospheric nitrogen fixing legumes. This limitation was bypassed using oxygen isotope analysis of nitrate in potato tubers, while hydrogen isotope analysis allowed complete discrimination of organic and conventional wheat and barley grains. It is concluded, that multi-isotopic analysis has the potential to disclose fraudulent substitutions of organic with conventionally cultivated plants.
authors.affiliation: Plant and Soil Science Section, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark. holst@life.ku.dk
authors.forename: K H
authors.initials: KH
authors.lastname: Laursen
authors.forename: A
authors.initials: A
authors.lastname: Mihailova
authors.forename: S D
authors.initials: SD
authors.lastname: Kelly
authors.forename: V N
authors.initials: VN
authors.lastname: Epov
authors.forename: S
authors.initials: S
authors.lastname: Bérail
authors.forename: J K
authors.initials: JK
authors.lastname: Schjoerring
authors.forename: O F X
authors.initials: OF
authors.lastname: Donard
authors.forename: E H
authors.initials: EH
authors.lastname: Larsen
authors.forename: N
authors.initials: N
authors.lastname: Pedentchouk
authors.forename: A D
authors.initials: AD
authors.lastname: Marca-Bell
authors.forename: U
authors.initials: U
authors.lastname: Halekoh
authors.forename: J E
authors.initials: JE
authors.lastname: Olesen
authors.forename: S
authors.initials: S
authors.lastname: Husted
mesh_terms: D002523:Edible Grain / Q000737:chemistry*; D005308:Fertilizers / Q000032:analysis; D058870:Food, Organic / Q000032:analysis*; D007554:Isotopes / Q000032:analysis*; D058871:Organic Agriculture; D010944:Plants / Q000737:chemistry*; D014675:Vegetables / Q000737:chemistry*
chemical_list: D005308:Fertilizers; D007554:Isotopes
keywords: Authenticity testing; Compound-specific; Denitrifier method; Fertilisers; Organic agriculture; Plants; Stable isotopes