Online Gas Chromatography Combustion/Pyrolysis-Isotope Ratio Mass Spectrometry (HRGC-C/P-IRMS) of (±)-Dihydroactinidiolide from Tea (Camellia sinensis) and Rooibos Tea (Aspalathus linearis)

Online capillary gas chromatography-isotope ratio mass spectrometry in both the combustion and the pyrolysis modes (HRGC-C/P-IRMS) was employed to perform authentication studies of the flavoring agent (+/-)-dihydroactinidiolide. Thus, the delta C-13(V-PDB) and delta H-2(V-SMOW) values of synthetic (ex synthetic beta-ionone and natural beta-carotene) as well as enzymatically (ex synthetic and natural beta-carotene) produced references were studied in comparison with those of the natural substance isolated from black (n = 17) and green teas (n = 6) (Camellia sinensis) as well as Rooibos tea (Aspalathus linearis) (n = 7). The isotope values determined for both the synthetic and enzymatically produced samples of (+/-)-dihydroactinidiolide reflected the influence of the origin of their educts. Hence, in cases when synthetic educts were used, the delta C-13(V-PDB) and delta H-2(V-SMOW) values ranged from -27.0 to -28.4 parts per thousand and from -28 to -169 parts per thousand, respectively, whereas the use of natural educts led to ranges from -30.3 to -31.6 parts per thousand and from -154 to -228 parts per thousand, respectively. As to the tea samples, delta C-13(V-PDB) and delta H-2(V-SMOW) values ranging from -29.0 to -34.1 parts per thousand and from -153 to -274 parts per thousand, respectively, were recorded for (+/-)-dihydroactinidiolide from black and green teas, whereas that from Rooibos tea showed H-2/H-1 ratios ranging from -189 to -210 parts per thousand as well as slightly enriched values in the C-13/C-12 ratios ranging from -24.4 to -27.1 parts per thousand.