Characterization of Tobacco Extracts by Gas Chromatography High Resolution Time of Flight Mass Spectrometry (GC-HRT)

High resolution time-of-flight mass spectrometry was used for comprehensive profiling of tobacco plant extracts.

The flavor and health risks of tobacco products are a direct result of their chemical composition. Alkaloids, organic acids, amino acids, saccharides, terpenes, and volatile aromatics are important contributors to tobacco leaf quality. It is well known that tobacco quality can vary significantly depending on where it is harvested. Comprehensive profiling is critical for understanding the chemical complexity responsible for aroma and flavor differentiation of tobacco leaves grown under different environmental conditions.

Experimental

Green leaf and cured tobacco extracts were analyzed using the Pegasus GC-HRT. The analysis workflow included EI-HRT and CI-HRT data acquisition to maximize the number of confidently identified metabolites. Instrument parameters are listed below:

Results and Discussion

Some of the major components in green leaf tobacco are terpenes, terpenoids, and sterols. An expanded analytical ion chromatogram (AIC) shows some of the plant sterols in the sample including campesterol, stigmasterol, sitosterol, and ?-Amyrin. The extracted ion chromatogram (XIC) illustrates the deconvolution power of LECO's ChromaTOF HRT software. The tocopherol and cholesterol MS spectral data is easily separated to provide high quality spectral data as shown by the excellent library match (LM = 880/1000) and mass accuracy value (-0.98 ppm) for cholesterol.

Table I: Representative compounds in green leaf tobacco extract

Tabular data for a representative set of additional compounds in the extract are listed in Table I. The quality of spectral data obtained using the GC-HRT is clearly evident from good library similarity matches (758–895/1000) and excellent mass accuracy values (Avg. = 0.95 ppm) which aided in library match confirmation for these analytes.

Figure 1: AIC (B) and XIC (A) of a green leaf tobacco extract. Peak true mass spectrum of cholesterol (C).

Conclusion

The Pegasus GC-HRT is an ideal tool for metabolomic profiling of plant extracts. Excellent mass accuracy values and high quality spectral data facilitated characterization of numerous classes of compounds in tobacco. For brevity, the CI-HRT data was not shown in this note, but will be included in a full application note at LECO.com.

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