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Chemometrics and stable isotope ratios of wine
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147420.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 24 november 2015Promotor : Buydens, L.M.C. Co-promotores : Wehrens, R., Camin, F.121 p
Potential use of the stable isotope ratios of bioelements and elemental composition to trace the origin of dairy products
No full textAccreditation of stable isotope ratio methods: guidelines for the implementation of a quality sistem according to ISO/IEC 17025:1999
No full textStable isotope techniques for detecting the authenticity of high value products
No full textConsumers are increasingly interested in health food, dietary supplements and natural compounds,
which command a higher price and are therefore subjected to adulteration. Methods for testing
authenticity of these products are therefore required.
Focus of the study is on the development of H, C and O stable isotope ratios analysis methods for this
purpose. Analysis of the isotopic ratio of C, O and H in the bulk samples was performed using an
isotope ratio mass spectrometer interfaced with an elemental analyser and a pyroliser. Moreover,
compound specific analysis of the 2
H/1
H, and 13C/12C was done using gas chromatographycombustion\pyrolisis-isotope
ratio mass spectrometry (GC-C\Py-IRMS). Stable isotope ratio of C can
distinguish olive oil squalene from shark squalene, Rosa damascena essential oil from Palmarosa oil,
Monacolin K naturally present in Red Yeast Rice from the prescription biosynthetic Lovastatin.
Moreover it allows to differentiate natural Vitamin C, Vanillin and Caffeine from the synthetic ones.
Stable isotope ratio of H discriminate natural from synthetic Curcumin, and in combination with the
stable isotope ratio of O, authentic Serenoa oil from the adulterated one. The stable isotope ratio
analysis can be used for verifying the authenticity of health foods, dietary supplement and natural
compounds commanding higher pric
IRMS, SNIF-NMR and proton NMR in wine analysis
Full text linkWine is an important element of world food industry; last year the wine production in EU was over 180 million hl (over 60% share of the world) and contributed over € 7 billion to EU trade balance. Such large markets always attract fraudulency and wine is no exception: in 2012 to 2015 counterfeit goods have cost € 59 billion, of these spirits and wine being € 2.7 billion. Therefore, effective control of such adulterations requires use of robust and reliable analytical methods for authentication of wines. One of these is isotope ratio mass spectrometry (IRMS), via which it is possible to measure ratios of nature stable isotopes of carbon, hydrogen and oxygen in wine. They depend on the origin of the compounds containing them and, therefore, allow for determining geographical origin of the samples and addition of water and exogenous sugar. Another approach is Site-specific Natural Isotopic Fractionation Nuclear Magnetic Resonance Spectroscopy (SNIF-NMR). By this method, the site-specific D/H isotope ratio in methylic and methylenic sites of ethanol is measured, and the values aid in determining the origin of ethyl alcohol in wine. In 1990s European Commission and International Organization of Vine and Wine (OIV) has adopted this method as a certified official method for analysis of wines. It is the only method based on NMR recognized as official standard. IRMS and SNIF-NMR methods are robust and reliable, but have some disadvantages, such as use of expensive standards, prolonged sample preparation, expensive equipment maintenance; also, the analysis is destructive in many cases. Over the recent years, a new approach for wine analysis emerged: proton NMR spectroscopy, which can be used for either targeted analysis, or non-targeted profiling. Compared to classical methods, proton NMR requires less sample preparation, less time to record the spectrum and has cheaper equipment maintenance costs. However, it has not yet been officially approved for food authentication
C and H stable isotope ratio analysis using GC-IRMS for vanillin authentication
No full textVanilla extracts are widely used as flavouring ingredients in foods and beverages and aromatic
compounds in perfumes and pharmaceuticals. Due to the high cost of producing high-quality
natural extracts from Vanilla planifolia, synthetic or natural identical biosynthetic vanillin (from
natural precursors such as guaiacol, ferulic acid, eugenol and lignin) are often used as a
substitute [1].
To verify the authenticity of vanilla extracts from Vanilla planifolia, one of the most commonly
used methods is stable isotope ratio analysis (SIRA) of 13C/12C (expressed as δ13C), since it
has been found that different plants discriminate differently against 13C and differently from the
synthetic source. Today this analysis is no longer enough to discover vanillin adulteration, due
to the practice of adding 13C to the methylic site of synthetic vanillin [2].
In this study, we combined analysis of 13C/12C with that of 2H/1H (expressed as δ2H) using GCIRMS
[3]. 16 authentic samples of Vanilla planifolia, 16 natural identical, 5 synthetic vanillin
and 20 commercial extracts were considered. Authentic natural vanillin from Vanilla planifolia
and natural identical vanillin are characterised by δ2H values much lower than those of
synthetic vanillin.
The isotopic values of all the commercial extracts declared to be from Vanilla planifolia
(N=20), had δ13C within the typical range for natural vanillin, but δ2H outside the range and
more similar to that of synthetic vanillin.
The combination of δ13C with δ2H GC-IRMS analysis of vanillin can therefore be proposed as
a suitable tool for improving the detection of vanilla extract adulteratio
Compound-specific analysis of δ13C and δ2H of olive oil fatty acids
No full textA method to determine δ13C, and for the first time δ2H of the main fatty acids extracted from olive oil triglycerides was developed. Triglycerides were subjected to base-catalysed transesterification with methanol to obtain the corresponding fatty acid methyl esters (FAMEs) in a one-step reaction. Then they were analysed through Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-C\Py-IRMS).
Here we present the validation data for the method, which were consistent with those of methods for the analysis of FAMEs in other matrices.
As there are no reference materials available, a standard mixture of FAMEs replicating the composition of olive oil was prepared and analysed to test the accuracy of measurement. The resulting δ13C and δ2H values were compared with the 'true' isotopic values of pure single FAMEs obtained with EA-IRMS and TC/EA-IRMS. The difference was no more than ±0.2‰ and ±1.9‰ for δ13C and δ2H. To assess precision, the reference FAMEs mixture was analysed 10 times with GC-C\Py-IRMS, the obtained mean standard deviations were ±0.2‰ and ±2‰ for δ13C and δ2H. Precision over a long period of time was monitored using quality control charts. The uncertainty of the whole process, from preparation to analysis, obtained by analysing one olive oil 10 times, was on average ±0.3‰ and ±3‰ for δ13C and δ2H (1s).
Finally the effects of adding carbon and hydrogen during methylation on δ13C and δ2H were evaluated.
The results demonstrated that the method presented can be used for precise and accurate determination of δ13C and δ2H of FAMEs from olive oil
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