Elemental and Isotopic Characterization of Tobacco from Umbria

Tracing the geographical origin of tobacco at two spatial scales by stable isotope and element analyses with chemometrics

Tobacco is a widely cultivated cash crop, but it is often smuggled and sold illegally. Unfortunately, there is currently no way to verify the origin of tobacco in China. In an effort to address this issue, we conducted a study using stable isotopes and elements from 176 tobacco samples at both provincial and municipal scales. Our findings revealed significant differences in δ¹³C, K, Cs, and ^208/206Pb at the provincial-level, and Sr, Se, and Pb at the municipal level. We created a heat map at the municipal level, which showed a similar cluster classification to geographic grouping and provided an initial assessment of tobacco origins. Using OPLS-DA modeling, we achieved a 98.3% accuracy rate for the provincial scale and 97.6% for the municipal scale. It is worth noting that the importance of rankings of variables varied depending on the spatial scale of the evaluation. This study offers the first traceability fingerprint dataset of tobacco and has the potential to combat mislabeling and fraudulent conduct by identifying the geographical origin of tobacco.

Stable isotope characterization of tobacco products: A determination of synthetic or natural nicotine authenticity

RATIONALE

"Tobacco-free" or synthetic nicotine products have appeared in some markets, increasing potential health risks and regulatory compliance challenges. Currently, there are few reliable methods for the determination of authenticity of natural and synthetic nicotine. Analytical techniques based on stable isotopes have broad application prospects in the traceability and identification of agricultural products.

METHODS

Tobacco leaves from four main tobacco production regions in China and different types of tobacco products were extracted with n-hexane and 5% sodium hydroxide to obtain nicotine extracts. Subsequent stable isotope mass spectrometry was performed by analyzing δ² H, δ¹³ C, and δ¹⁵ N values of nicotine.

RESULTS

Firstly, results from a batch of 233 samples indicated stable isotopes were closely related to climate and geographical locations and provide a basis for a determination of the origin of tobacco leaves. In addition, the δ² H values had significant differences between natural and synthetic nicotine and the results indicate a δ² H value of -163.0‰ could be the threshold for assessing synthetic and natural nicotine. Finally, a total of 239 results further validated the δ² H value as a metric for source authentication of commercial tobacco products.

CONCLUSIONS

Synthetic (S)-(-)-nicotine could be accurately and quickly identified using the method developed by measuring δ² H values in a qualitative manner. To our knowledge, this is the first time a stable isotope mass spectrometry technique has been used for distinguishing the source of nicotine. This technique will aid in the accurate identification, labelling, and regulation of synthetic nicotine-based tobacco products.

Dokha brand differentiation by elemental analysis measured by inductively coupled plasma-mass spectrometry

Dokha is a tobacco product commonly used in Middle Eastern and Northern African regions. It is available in three blends purportedly corresponding to the degree of "buzz" experienced by the user. The "buzz" has been linked in part to nicotine levels, which are higher than those found in cigarettes and is believed to be the reason dokha is abused as a "legal high." There have been reports of seizure activity from dokha users, and elevated concentrations of toxic metals have been measured in dokha tobacco. The purpose of this work was to determine whether we could use dokha's elemental content, measured by inductively coupled plasma-mass spectrometry, to link dokha back to its brand. This could aid investigators in identifying brands and/or distribution routes in the case of adverse effects resulting from dokha use. We measured the concentrations of Mg, K, Mn, Ni, Cu, Rb, Sr, and Ba in Medwakh, Nirvana, Scorpion, Enjoy, Kingdom, and Iconic dokha brands. Analysis of variance revealed statistical differences in concentrations of elements among groups. Discriminant function analysis (using leave-one-out classification) was 58.3% successful at differentiating brands. Enjoy dokha was the most, and Kingdom dokha the least, correctly classified among groups. Attempts to further link dokha blends back to light, medium, and heavy blends were less successful. These results indicate potential for using elemental content to discriminate among dokha brands. Our data may also help to understand the degree of additional processing and/or adulteration of dokha products available to users in the United States.