Search For Non-Volatile Components With Low Polarity Characterizing Tobacco Leaves Using Liquid Chromatography / Atmospheric Pressure Chemical Ionization Mass Spectrometry Detector
There has been focus on the components with low polarity in tobacco leaf resin due to their probable relation with taste and aroma of tobacco products, the lack of a feasible analytical method and instrument has long been an obstacle to identifying the components with low polarity. The author thereby paid attention to the analysis employing nonaqueous reversed-phase chromatography hyphenated with a photo diode array detector and an atmospheric pressure chemical ionization mass spectrometry detector which has been considered applicable to the separation of significant but unknown non-volatile. The application succeeded in simultaneously separating, detecting and quantifying more than 100 non-volatile components with different low polarity such as solanesols, triacylglycerols, phytosterols, and chlorophylls. However, their compositional differences among various tobacco leaves still remained partial knowledge based on targeted analysis instead of global knowledge based on comprehensive analysis. No investigation searching for key components elucidating different tastes, aromas, species, cultivars, curing processes, and growing districts among tobacco leaves has been carried out so far. For this reason, all the quantification data were consolidated to form complete multidimensional matrix and were statistically processed to observe the categories and the key components of various tobacco leaves by principal component analysis and hierarchical clustering analysis. Tobacco leaves were first classified into three categories consisting of flue-cured Virginia, air-cured leaf, and Oriental. Solanesyl esters, phytosteryl esters and solanachromene contributed to the category of flue-cured Virginia, while air-cured leaf was characterized by free phytosterols. Oriental was featured by chlorophyll in addition to the contributory components to flue-cured Virginia. Non-volatile components with low polarity seemed to be degraded during curing process and to therefore characterize the different curing processes among various tobacco leaves.