Determination of 2H/1H and 13C/12C isotope ratios of (E)-methyl cinnamate from different sources using isotope ratio mass spectrometry.
For the authenticity assessment of (E)-methyl cinnamate from different origins, combustion/pyrolysis-isotope ratio mass spectrometry (C/P-IRMS) was used by an elemental analyzer (EA) and on-line capillary gas chromatography coupling (HRGC-C/P-IRMS). For that reason, (E)-methyl cinnamate self-prepared from synthetic, natural, and semisynthetic educts was analyzed in comparison to the commercial synthetic and natural ester. In addition, (E)-methyl cinnamate from basil extract and a number of commercial natural aromas was investigated. The data of self-synthesized synthetic (E)-methyl cinnamate, i.e., delta(13)C(V)(-)(PDB) = -33.8 per thousand and delta(2)H(V)(-)(SMOW) = +349 per thousand, corresponded with that found for the commercial synthetic samples (-29.5 to -31.4 per thousand and +328 to +360 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively). The ester produced from natural educts by acid as well as Candida antarctica catalysis revealed delta(13)C(V)(-)(PDB) = -25.6 and -30.1 per thousand as well as delta(2)H(V)(-)(SMOW) = -162 and -169 per thousand, respectively. Acid-catalyzed semisynthetic products differed in their delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) values depending on the origin of their educts. For the ester from synthetic methanol and natural cinnamic acid, -27.3 and -126 per thousand were determined for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively, whereas for the ester produced from natural methanol and synthetic acid delta(13)C(V)(-)(PDB) = -30.6 per thousand and delta(2)H(V)(-)(SMOW) = +287 per thousand were found. Basil extract showed -28.9 and -133 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. Commercial aromas declared to be natural revealed delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data ranging from -25.7 to -28.5 per thousand as well as -85 to -191 per thousand, respectively, indicating, in part, incorrect declaration.
Fink
Kathrin
K
Lehrstuhl für Lebensmittelchemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Richling
Elke
E
Heckel
Frank
F
Schreier
Peter
P
D002247:Carbon Isotopes / Q000032:analysis; D002934:Cinnamates / Q000032:analysis*; D003903:Deuterium / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D007554:Isotopes; D013058:Mass Spectrometry / Q000379:methods*; D018649:Ocimum basilicum / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry
D002247:Carbon Isotopes; D002934:Cinnamates; D007554:Isotopes; D010936:Plant Extracts; C025385:methyl cinnamate; D003903:Deuterium