Phenols are known toxic substances and accordingly it is recognized that it would be desirable to reduce the levels of phenol and other phenolic compounds found in the semi-volatile fraction of mainstream cigarette smoke. Whilst it is also well-known that cellulose acetate filters plasticized with triacetin exhibit enhanced selective filtration of phenol, there is an ongoing need for filter materials that provide still further enhancement of the removal of phenols.

During this work, a range of liquid additives that may be expected to improve the selective filtration of phenols was identified. A laboratory technique for screening the performance of these additives was developed, in particular to overcome uncertainties arising from interactions between the additive and the choice of filter substrate material (e.g. paper or cellulose acetate).

This paper describes the laboratory techniques developed, together with the results from smoking tests carried out on the identified additives over a range of application levels. It was concluded that the greatest levels of enhanced selective filtration of phenols were obtained from glycerol tripropionate. The results from further trials conducted on this material to assess whether the enhanced performance was maintained on machine-made cellulose acetate filters over a three month ageing period are also reported.