Site-specific natural isotope resonance

More recently, enantiomer ratios have been used as evidence of adulteration in natural foods and essential oils. If the enantiomer distribution of achiral component of a natural food does not agree with that of a questionable sample, then adulteration can be suspected. Chiral GC analysis alone may not provide adequate evidence of adulteration, so it is often used in conjunction with other instrumental methods to completely authenticate the source of a natural food. These methods include isotope ratio mass spectrometry (IRMS), which determines an overall 13C/12C ratio (Mosandl, 1995), and site-specific natural isotope fractionation measured by nuclear magnetic resonance spectroscopy (SNIF-NMR), which determines a 2H/ H ratio at different sites in a molecule (Martin et al 1993), which have largely replaced more traditional analytical methods using GC, GC-MS, and HPLC. [Pg.1037]

SD standard deviation SDE simultaneous distillation extraction SDS sodium dodecyl sulfate SFC solid fat content SFI solid fat index SHAM salicylhydroxamic acid SIM selected ion monitoring SNIF-NMR site-specific natural isotope fractionation measured by nuclear magnetic resonance spectroscopy SP-HPLC straight-phase high-performance liquid chromatography... [Pg.1309]

Cotte, J. F., Casabianca, H., Lheritier,J., Perrucchietti, C., Sanglar, C., Waton, FI., and Grenier-Laustalot, M. F. (2007). Study and validity of 13C stable carbon isotope ratio analysis by mass spectrometry and 2H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey. Anal. Chim. Acta 582,125-136. [Pg.159]

The first paper dealing with the NMR determination of non-random distribution of deuterium appeared in 1981 and the site-specific natural isotope fractionation studied by nuclear magnetic resonance (SNIF-NMR) terminology was proposed.36 Since this time several review articles on application of deuterium and 13C NMR natural abundance spectroscopy were published.37 1... [Pg.153]

Due to the inability to reliably detect beet sugar additions, the site-specific natural isotope fractionation nuclear magnetic resonance (SNIF-NMR) method used widely in the wine industry was adapted for the maple industry (Martin et al., 1996). This method determines the site specific isotope concentrations of organic compounds by nuclear magnetic resonance of ethanol fermented from the suspect sample. [Pg.138]

The biosynthetic origins of vanillin can be determined by the analysis of naturally occurring isotope ratios (in practice, chiefly 2H/1H and 13C/12C), using isotope ratio-mass spectrometry (IR-MS) and nuclear magnetic resonance (site-specific natural isotope fractionation SNIF-NMR ). Isotopic ratio... [Pg.300]

Martin, G.J., Martin, M.L. and Zhang, B.-L. (1992) Site-specific natural isotope fractionation of hydrogen in plant products studied by nuclear magnetic resonance. Plant, Cell and Environment 1 5, 1 037-1 050. [Pg.310]

Site-specific measurement of isotope ratios can be made using site-specific natural isotope fractionation-nuclear magnetic resonance (SNIF-NMR). This was first proposed in 1981 by Martin and Martin [30], who then applied it to the adulteration of food (wine) in 1988 [31]. This technique allows D H ratios for specific H atoms within a molecule to be measured and can provide additional... [Pg.126]

An NMR spectrometer for SNIF-NMR (Fig. 6.17) (site-specific natural isotope fractionation NMR) measurements [226] must be specifically equipped and adapted, e.g. for deuterium analysis by a high field magnet (e.g. 9.4 T, corresponding to 400 MHz ( H) and 61.4 MHz ( H) resonance frequency, or 11.4 T, corresponding to 500 MHz ( H) and 76.8 MHz ( H) resonance frequency), a specifically adapted H-NMR probe with fluorine lock and proton decoupling, highly stable electronics and software for spectra acquisition and data processing/treatment. Instrumental details... [Pg.616]

Due to the complexity of food matrices several advanced spectroscopic techniques have recently been successfully employed to solve authenticity problems, including near infrared spectroscopy (NIR), mid infrared spectroscopy (MIR), low- and high-field nuclear magnetic resonance (NMR), site-specific natural isotopic fiactionation (SNIF-NMR) and... [Pg.158]

Spectroscopic techniques used in essential oil analysis comprise ultraviolet and visible spectrophotometry, infrared spectrophotometry (IR), mass spectrometry (MS), and nuclear magnetic resonance spectroscopy (NMR), including the following H-NMR, C-NMR, and site-specific natural isotope fractionation NMR. Combined techniques (hyphenated techniques) employed in essential oil analysis are GC/MS, liquid chromatography/mass spectrometry, gas chromatography/Fourier transform infrared spectrophotometry (GC/FT-IR), GC/FT-IR/MS, GC/atomic emission detector, GC/isotope ratio mass spectrometry, multidimensional GC/MS. [Pg.393]

V. Caer, M. Trierweiler, G.J. Martin, M.L. Martin (1991) Determination of site-specific carbon isotope ratios at natural abundance by carbon-13 nuclear magnetic resonance spectroscopy. Anal. Chem. 21, 2306-2313... [Pg.657]

Stable isotope ratio analysis (SIRA, GC-IRMS [Gas Chromatography-Isotope Ratio Mass Spectrometry], and Site Specific Isotope Fractionation — Nuclear Magnetic Resonance [SNIF-NMR]) have proven useful in many adulteration situations. In nature, and exist at relative proportions of 1.11 98.89 [27]. The photosynthetic process selectively enriches the plant in dependent upon the type of photosynthetic process used by the plant. Plants using the Hatch-Slack pathway (e.g., com, sugar cane, millet, and lemon grass) give 8 C values the closest to the standard, i.e., 5 C values of ca. -10. The 5 C value is calculated as ... [Pg.461]