Online determination of 2 H/ 1 H and 13 C/ 12 C isotope ratios of cinnamaldehyde from different sources using gas chromatography isotope ratio mass spectrometry

Abstract

The combination of gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) and gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-P-IRMS) is applied to the authenticity assessment of cinnamaldehyde from various sources. For that reason, cinnamon oils were self-prepared by steam distillation from three different varieties of cinnamon bark on the market, C. ceylanicum (ceylon), C. cassia (cassia) and C. burmanii (cassia vera). Furthermore, the so-called wood cinnamon was investigated, which is produced from the outer bark of older branches of cinnamon of minor quality. Self-prepared oils were analysed from commercial cinnamon powder. In addition several commercial samples of cinnamon oil and cinnamaldehyde, some of them declared to be natural, were investigated. δ 2ΗV-SMOW and δ 13CV-PDB values of cinnamaldehyde were determined and characteristic authenticity ranges were deduced, allowing the differentiation between synthetic and natural samples. By correlation of both the δ 2ΗV-SMOW and δ 13CV-PDB values, characteristic authenticity ranges were defined for ceylon, cassia and wood cinnamon. The δ 2ΗV-SMOW and δ 13CV-PDB values of cassia vera samples are in the range of cassia. By comparing the δ 2ΗV-SMOW values of different self-prepared samples (ground bark, distillate) of cinnamon determined by TC/EA-IRMS with the corresponding GC-IRMS values, online GC-IRMS methods are proved to be essential in the authentication of complex natural products.