Parameters Affecting the Selective Filtration of Certain Tobacco Smoke Components

The purpose of this investigation was to attain a better understanding of the selective removal of certain compounds from cigarette smoke by filters. A gas chromatographic method for the determination of selected semivolatile smoke compounds was developed. The method, which utilizes a 160 m glass capillary column, was used to determine the efficiency of filters for the removal of these selected semivolatile compounds. A correlation was found between the selective filtration of these compounds from cigarette smoke and their distribution coefficients [K_d = (g compound/g filter)/ (g compound/cm³ air)] between air and various filter materials. In addition, a correlation was found between the physicaI and chemical nature of certain smoke compounds and their selective filtration. Previous work indicated that if a compound is to be selectively removed from tobacco smoke by a filter, [1] a significant portion of that compound should be in the vapour state as it passes through the filter and [2] the compound should have an affinity for the filter material. The relative rate of vapourization (R_v) was used as a measure of 1., and the totaI solubility parameter (d) was taken as a measure of 2. Values for the vapourization rate were calculated from the product, vapour pressure (P), molecular weight (M), and diffusion coefficient (D), (R_v = kPMD^1/2). The correlation of R_v and δ with the selectivity (S_x) of cellulose acetate filters for smoke compounds is described by

S_x = b₀ + b₁δ + b₂δ (1n R_v),

where b₀, b₁, and b₂ are constants. This equation may be used to predict the selective filtration of semivolatile compounds from cigarette smoke.