Authenticity assessment of estragole and methyl eugenol by on-line gas chromatography-isotope ratio mass spectrometry

On-line capillary gas chromatography-isotope ratio mass spectrometry was used in the combustion (HRGC-C-IRMS) and the pyrolysis (HRGC-P-IRMS) modes to determine delta(13)C(PDB), delta(2)H(SMOW), and delta(18)O(SMOW) data of estragole (1) and methyl eugenol (2) originating from various sources. For 1, similar delta(13)C values, i.e., ranging from -35.4 to -29.9 per thousand and from -36.4 to -28.8 per thousand for the product of synthetic and natural origins, respectively, were found. The delta(2)H values ranged from -155 to -3 per thousand for synthetic 1 and from -193 to -105 per thousand for 1 from natural origin, whereas the determination of delta(18)O data gave values from +1.8 to +24.8 per thousand and from +2.7 to +18.7 per thousand for 1 from synthetic and natural origins, respectively. As synthetic 2 is produced by methylation of natural eugenol, the IRMS techniques did not allow differentiation of synthetic 2 from the product of natural origin. The recorded data ranges were nearly identical, i.e., delta(13)C = -37.4 to -35.0 per thousand and -41.1 to -32.2 per thousand; delta(2)H = -155 to -126 per thousand and -217 to -107 per thousand; delta(18)O = +5.5 to +6.6 per thousand and +2.7 to +6.9 per thousand, each for 2 from synthetic and natural origins, respectively.