Chemical and biological assays showed that wool filters containing mixtures of commercially available polyethylenimines (PEI) and quaternary ammonium compounds (QUAT) selectively removed proportions of the biologically active volatile constituents of cigarette smoke. The action of the QUAT was synergistic in that it enhanced the performance of PEI filters but, alone, was ineffective in retaining volatile components. Only water-soluble QUATs with one long hydrocarbon chain (> 10 C-atoms) attached to nitrogen were effective. The best removal efficiencies were obtained with a PEI/QUAT ratio in the range 0.8-1.0 and 5-10 % by weight of each additive on the filter material. Analyses of puffs at stages along the tobacco column indicated that the treated filters retained their effectiveness from the first to the last puffs. The treated filters significantly increased the pH of the mainstream smoke.
Modified-wool cigarette filters have been evaluated for their efficiency in selectively retaining specific biologically active volatile and semivolatile smoke components. Filters containing chemically modified wools or wool treated with low-molecular-weight additives were ineffective. Polymeric additives reduced the cytotoxic level of cigarette smoke by varying degrees. Polyethylenimines were particularly effective additives and selectively removed portions of formaldehyde, acetaldehyde, acrolein, hydrogen cyanide, phenols and other weakly acidic compounds. Increasing the moisture content of the treated filters markedly improved their performance. The effectiveness of polyethyleniminetreated filters in removing volatile aldehydes was strongly dependent on the pH of the filter, most efficient removaI occurring at pH 6.0-6.2.