Quantitative analysis using gas chromatography/combustion/isotope ratio mass spectrometry and standard addition of intrinsically labelled standards (SAIL)--application to isoflavones in foods.
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.
Bluck
Leslie J C
LJ
MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK. les.bluck@hnr.can.ac.uk
Jones
Kerry S
KS
Thomas
Jane
J
Liggins
Jason
J
Harding
Marilyn
M
Bingham
Sheila A
SA
Coward
W Andrew
WA
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
D002247:Carbon Isotopes; D004968:Estrogens, Non-Steroidal; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D019833:Genistein