Stability and Concentrations of Humectants in Tobacco

Humectants, especially glycerol and propylene glycol, are tobacco additives that are used to facilitate several processes in the production of tobacco products and to maintain the moisture content. Humectants in tobacco are usually detected by gas chromatography with flame ionization detection after a pre-analytical conditioning procedure. During this conditioning step, significant decreases of especially propylene glycol levels were observed. The goal of the present study is to find out the reason for this decrease, and to propose a method that minimizes this loss. Therefore, detailed studies were performed directed to this problem, which revealed that evaporation is the most likely source of this loss. Based on our findings, we propose a method without a pre-analytical conditioning step. Using the present method, in 10 different brands of commercially available cigarettes it was checked whether the measured concentrations of the humectants correspond with the declared concentrations as supplied by the manufacturers. The analysis showed that the measured levels were in general much lower than the specified amounts, possibly due to evaporation during processing tobacco to cigarettes. Therefore, it was suggested that the manufacturers should also specify the final amounts of humectants in cigarettes after the manufacturing process.