title: Quantitative analysis using gas chromatography/combustion/isotope ratio mass spectrometry and standard addition of intrinsically labelled standards (SAIL)--application to isoflavones in foods.
abstract: We have investigated a novel application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for the quantitative analysis of the isoflavones in food matrices. Previous methods have been hampered by the lack of analytical standards to introduce early enough in the extraction procedure to allow compensations for losses at all stages of the procedure. In this work we have produced standard materials that can be added at the initial extraction, by intrinsically labelling soya plants by growing them in an atmosphere enriched in the stable isotope of carbon in CO(2). On analysis these plants were shown to contain phytoestrogens at a high (up to 20%) level of enrichment. The dried plant material has been used to estimate the isoflavone concentrations of a set of spiked flours. For daidzein the methodology was shown to produce results comparable to those achieved by GC/MS techniques. The method was less successful for genistein, possibly due to the greater fragility of this compound under the conditions required for the analysis.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK. les.bluck@hnr.can.ac.uk
authors.forename: Leslie J C
authors.initials: LJ
authors.lastname: Bluck
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Jones
authors.forename: Jane
authors.initials: J
authors.lastname: Thomas
authors.forename: Jason
authors.initials: J
authors.lastname: Liggins
authors.forename: Marilyn
authors.initials: M
authors.lastname: Harding
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Bingham
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Coward
mesh_terms: D002247:Carbon Isotopes; D004968:Estrogens, Non-Steroidal / Q000032:analysis; D005433:Flour; D005504:Food Analysis / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D019833:Genistein / Q000032:analysis; D007529:Isoflavones / Q000032:analysis*; D048789:Phytoestrogens; D028321:Plant Preparations; D012016:Reference Values; D013025:Glycine max / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D019833:Genistein