Stable carbon isotope ratio analysis

The determination of the isotopic composition of the carbon in organic compounds has become a useful tool in differentiating between natural and synthetic products. Both the determination of the stable isotopic ratio of and and the determination of the 0 have been sucessfully applied to a variety of products to determine sophistication (10, 11). Since the application of GC isolation and stable isotope ratio analysis was successful in the detection of vanilla/vanillin sophistication (4), it was decided to apply the same methodology to cinnamon/cinnamic aldehyde. As can be seen from Table 1, this procedure could not differentiate between natural and synthetic cinnamic aldehyde the natural compound apparently is biosynthesized via the Calvin cycle, and synthetic... 

Carbon stable isotope ratio (CSIR) analysis of sugar utilizing an isotope ratio mass spectrometer (IRMS) is routinely used to detect the addition of cane sugar and corn syrup to most juices with the exception of pineapple. The inability of CSIR analysis to detect beet sugar in orange and apple juices because of metabolic similarities between adulterant and authentic products has required alternative methods, e.g., combination of IRMS and nuclear magnetic resonance (NMR) spectroscopy. The method requires the determination of five isotope ratios after fermentation of the juice the H/ H and iSq/ISo ratios of the fermentation water plus the total C/ C and H/ H ratios on the methyl and methylenic groups of the alcoholic distillate. 

Stable isotope ratio analysis Adulteration of fruit juices or honey by addition of bulk sweeteners can be detected by stable isotope ratio mass spectrometric analyses, because the naturally occurring carbon isotope ratio of to in honey and fruit is different from that in corn or sugarcane although not from that in sugar beet. The oxygen isotope ratio may be used for beet sugar addition. 

Kurashima, N., Makino, Y., Sekita, S., Urano, Y., Nagano, T. (2004) Determination of origin of ephedrine used as precursor for illicit methamphetamine by carbon and nitrogen stable isotope ratio analysis. Anal. Chetn., 76, 4233 236. 

Although GC-C-IRMS systems that can measure the chlorine isotopic composition of individual chlorinated hydrocarbons are currently unavailable, it is clear that chlorine isotope analysis is also a useful technique to consider for study [614,677,678]. Measurement of chlorine stable isotope ratios in natural samples such as rocks and waters has become routine [626,679,680], but few measurements of chlorine isotopes in chlorinated aliphatic hydrocarbons have been reported [614]. A chlorine isotope effect was found in ferf-butyl chloride [681], demonstrating that 37Cl is more strongly bound to carbon than is 35Cl. Significant differences in the <5i7Cl values of some atmospheric chlorinated... 

A reliable authenticity assessment is concluded from the simultaneous consideration of multielement IRMS and enantioselective analysis. The differences of the stable isotope ratios of linalool and linalyl acetate are depicted as a three-dimensional plot of A values (d values of linalool minus d values of linalyl acetate for oxygen, hydrogen and carbon) (Fig. 17.15). This plot shows that the commercial samples S1-S5 are different from all the other samples investigated. Linalool and linalyl acetate of S1-S5 definitely are not genuine lavender oil compounds. 

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. 

Giraudon, S., Danzart, M., and Merle, M. H. (2000). Deuterium nuclear magnetic resonance spectroscopy and stable carbon isotope ratio analysis/mass spectrometry of certain monofloral honeys.. AOAC Int. 83,1401-1409. 

Lorrain, A., N. Savoye, L. Chauvaud, Y-M. Paulet, and N. Naulet. 2003. Decarbonation and preservation method for the analysis of organic C and N contents and stable isotope ratios of low-carbonated suspended particulate material. Anal. Chim. Acta 491 125-133. 

Lee, K., Gillatt, P. and Rossell, J.B. (1993) Authenticity of edible vegetable oils and fats, Part XX determination of maize oil purity by stable carbon isotope ratio analysis (SCIRA). Leatherhead Food RA Research Reports No. 719. Leatherhead Food RA, UK. 

J 5). Average analytical variability of sample preparation and stable carbon isotope ratio analysis is +0.2 (1 ). A Carlo-Erba Model 1106 Elemental Analyzer was employed to determine percent organic carbon and nitrogen in each sediment sample. Analytical variation of sample analysis is 20 (17). 

The isotopic distribution found in natural F F compounds serves as a signature that analysts can use to differentiate natural compounds from synthetic analogs. The metabolic pathways that plants use to create carbon compounds discriminate between C and C. The C/ C ratio of the carbon dioxide the plant uses as a reactant differs from the C/ C ratio of the compounds the plant produces. Stable carbon isotope ratio analysis (SIRA) measures the C/ C ratio and can authenticate the natural or synthetic origins of some F F materials. SIRA applied to isotopes of hydrogen, or D and H can also serve to authenticate natural F F materials. When combined with GC the on-line or D/ H SIRA analysis can authenticate each component in a complex mixture such as a cinnamon bark oil (19). 

Boutton, T. W., 1991. Stable isotope ratios of natural materials 1. Sample preparation and mass spectrometric analysis. In Coleman, D. C. B. Fry (eds.) Carbon Isotope Techniques. Academic Press, New York 155-171. 

Sealy, J. (1997) Stable carbon and nitrogen isotope ratios and coastal diets in the Later Stone Age of South Africa a comparison and critical analysis of two data sets. Ancient Biomolecules 1, 131 147. 

---