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 This application claims priority from U.S. Provisional Application Ser. No. 60/309,38S, filed Aug. 1, 2001, which application is incorporated herein by reference in its entirety, from U.S. Provisional Application Ser. No. 60/309,435, filed Aug.1, 2001, which application is incorporated herein by reference in its entirety and U.S. patent application Ser. No. 10/011,841, filed Oct.30, 2001.
 The present invention relates to a cigarette filter that includes a smoke constituent adsorbent which, when combined with a carbon-based filtering material, demonstrates synergistic reductions in smoke vapor constituents.
 Cigarettes include tobacco rods or columns which, when burned, produce a particulate and a vapor phase. About 70 years ago, filters began to be attached to an end of the tobacco column. Among other things, the filter removed various smoke components. Filters made from filamentary or fibrous material, such as cellulose acetate tow or paper, remove the particulate phase of tobacco smoke by mechanical means. However, the fibrous materials are not effective at removing volatile constituents, such as aldehydes, hydrogen cyanide and sulfides, which are found in the vapor phase. Typically, an adsorbent or absorbent is combined with the fibrous material to improve removal of the vapor phase components. For example, cigarette filters have included activated carbon, porous minerals such as meerschaum, silica gel, cation-exchange resins and anion-exchange resins.
 Charcoal has a high specific surface area and is a relatively strong adsorbent for vapor-phase constituents of tobacco smoke. When coated with a mixture of metallic oxides, charcoal is particularly effective in removing acidic gases. Meerschaum has a large adsorption area with a strong adsorption affinity for charged species, but a considerably low adsorption affinity for non-polar species. Silica gels are generally regarded as weakly retentive adsorbents for vapor-phase constituents of tobacco smoke. Although silica gel readily adsorbs aldehydes and hydrogen cyanide, the constituents also readily desorb from the silica gel. Cation exchange resins have been proposed for nicotine removal. Anion exchange resins have been proposed for the removal of smoke acids, but strongly basic anion exchangers have no effect on smoke vapor phase aldehydes. Weakly basic anion-exchange resins of porous structure are suitable for the removal of smoke acids and aldehydes, but their efficiency diminishes during smoking, as does that of carbon and porous minerals.
 Two or more adsorbents can be used in combination in cigarette filters. For example, U.S. Pat. No.2,815,760 describes the use of an ion exchange material with materials which “chemically react with the harmful, nonalkaline and nonacid components of the smoke to form non-volatile compounds, thus retaining the latter to the filter.” However, the aforesaid additives have not yielded satisfactory selective removal of such smoke phase components, as smoke aldehydes, particularly acetaldehyde and acrolein. U.S. Pat. No.4,300,577 describes the use of a weakly retentive absorbent for vapor-phase constituents intermingled with a second component having mainly primary amino functional groups for the removal of vapor-phase constituents, including aldehydes and hydrogen cyanide from tobacco smoke. However, the filter of the '577 patent has not been shown to demonstrate adequate consumer acceptance or commercial viability.
 The present invention relates to a cigarette filter that includes a multiple section filter which reduces the level of predetermined smoke constituents. The filter consists of a fibrous filter plug located at the mouth-end of the cigarette, a section containing a selective adsorbent material, and a section containing a general adsorbent material.
 The filter plug can be any filter plug known in the art, such as cellulose acetate tow. The general adsorbent material is preferably selected from a group of relatively high surface area materials, such as activated charcoal, which are capable of adsorbing a range of chemical compounds without a high degree of specificity. The selective adsorbent material is chosen based on the specific smoke constituents targeted for removal. Preferably, the selective adsorbent material is selected from a group of surface functionalized resins, wherein each resin consists of an essentially inert carrier with a surface area of greater than about 35 m
 Structurally, the selective adsorbent material may be adjacent to a tobacco rod and the general adsorbent material positioned between the selective adsorbent section and the filter plug. Alternatively, the general adsorbent material may be positioned adjacent to the tobacco rod and the selective adsorbent material between the general adsorbent section and the filter plug. Preliminary data indicates that the former orientation produces a synergistic effect in smoke constituent reductions relative to the latter orientation. Further, the selective adsorbent and general adsorbent may be interspersed in a traditional filter plug material, such as cellulose acetate, or the adsorbents may be packed as a bed or thin layer sections within filter plug material.
 The cigarette filter of the present invention includes a multiple section filter which reduces the levels of predetermined smoke constituents. The filter consists of a fibrous filter plug located at the mouth-end of the cigarette, a section containing a selective adsorbent material, and a section containing a general adsorbent material.
 As shown in
 In the present invention, as shown in
 The filter plug
 The general adsorbent section
 The selective adsorbent section
 Further, the selective adsorbent material
 When the cigarette is consumed, the tobacco smoke is puffed by the smoker through the filter
 In a first example embodiment of the present invention, as shown in
 As shown in
 In an alternative embodiment, such as shown in
 As shown in another embodiment in
 An advantage of the embodiment
 As shown in
 The following examples are representative of the embodiments which can be prepared in accordance with the present invention and the smoke constituent removal performance of those embodiments. The embodiments presented are intended for example purposes only and are not intended to be limiting in scope.
 A cigarette
 A cigarette
 Cigarettes are prepared as in Example 1 except that about 20 mg Duolite A7 is used in the selective adsorbent section
 Cigarettes are prepared as in Example 2 except that about 20 mg Duolite A7 is used in the selective adsorbent section
 Cigarettes are prepared as in Example 1 except that about 60 mg Duolite A7 is used in the selective adsorbent section
 Cigarettes are prepared as in Example 2 except that about 60 mg Duolite A7 is used in the selective adsorbent section
 Cigarettes are prepared as in Example 1 except that about 69 mg of a mineral-based charcoal made from semi-anthracite coal is used in the general adsorbent section
 Cigarettes are prepared as in Example 2 except that about 69 mg of a mineral-based charcoal made from semi-anthracite coal is used in the general adsorbent section
 Representative cigarettes of Examples 1-6 are smoked to a butt length of about 4 mm from the tipping using a Borgwalt RM-20 smoking machine. Following the procedures set forth by the FTC, smoke constituents exiting the filter end of each cigarette are passed through a Cambridge filter pad, the vapor phase is collected in a bag and analyzed by GC/MS. The data is normalized to about 10 mg tar per cigarette.
Average Vapor Phase Yields (μg/cig) Cigarettes Prepared by Example: 1 2 3 4 5 6 mg Duolite/ cigarette 40 20 60 Filter Segment CA/GA/ CA/SA/ CA/GA/ CA/SA/ CA/GA/ CA/SA/ Order SA GA SA GA SA GA Acetaldehyde 330.9 333.7 380.7 346.2 320.3 310.9 Isoprene 231.4 240.4 252.1 246.1 227.4 227.2 Acetone 144.1 163.5 156.0 160.5 148.0 151.4 Methanol 104.9 127.6 114.5 142.8 111.7 98.5 Acetonitrile 59.8 72.0 67.0 77.4 62.8 57.3 Acrolein 29.6 31.4 33.6 32.2 28.5 29.9 Methyl ethyl 29.3 35.9 30.9 38.5 30.1 31.6 ketone Formaldehyde 23.5 25.8 25.5 25.0 22.1 24.5 Propionalde- 25.7 27.4 29.3 28.5 25.3 25.0 hyde 1,3-Butadiene 25.5 25.9 27.5 25.5 25.8 25.0 Toluene 22.5 25.3 22.0 27.5 23.9 22.5 Benzene 20.6 23.6 21.6 24.1 21.1 21.4 Acrylonitrile 16.8 17.7 18.0 18.0 17.0 16.5 Furan 16.2 17.0 17.3 16.4 16.4 16.2 Hydrogen 15.1 16.4 20.7 19.6 13.6 14.8 cyanide Hydrogen 12.9 13.0 14.0 12.9 13.1 12.7 sulfide Propionitrile 12.9 15.0 13.5 15.9 13.6 12.8 2- 6.4 6.7 7.0 7.0 6.6 6.4 Methylpropanal Crotonaldehyde 5.1 5.9 5.5 6.3 5.3 5.0 Carbon 2.5 2.6 2.7 2.6 2.6 2.5 disulfide Styrene 2.0 1.8 2.2 1.9 2.1 1.7 Pyridine 1.9 1.9 1.9 1.8 1.9 1.8
 Representative cigarettes of Examples 7 and 8 are smoked to a butt length of about 4 mm from the tipping using a Borgwalt RM-20 smoking machine. Following the procedures set forth by the FTC, smoke constituents exiting the filter end of each cigarette are passed through a Cambridge filter pad, the vapor phase is collected in a bag and analyzed by GC/MS. The data is normalized to about 10 mg tar per cigarette.
Average Vapor Phase Yields (μg/cig) Cigarettes Prepared by Example: 7 8 mg Duolite/cigarette 40 Filter Segment Order CA/GA/SA CA/SA/GA Acetaldehyde 343.4 364.2 Isoprene 225.0 268.9 Acetone 138.6 162.3 Methanol 95.1 134.7 Acetonitrile 61.4 84.6 Acrolein 9.8 35.3 Methyl ethyl ketone 28.3 39.8 Propionaldehyde 26.4 30.2 1,3-Butadiene 25.4 27.7 Toluene 18.7 24.2 Benzene 21.3 27.3 Acrylonitrile 7.5 9.0 Furan 17.0 18.4 Hydrogen cyanide 16.7 19.5 Hydrogen sulfide 14.7 14.1 Propionitrile 15.7 20.3 2-Methylpropanal 13.0 14.8 Crotonaldehyde 3.3 5.1 Carbon disulfide 2.8 2.8 Styrene 1.8 2.1 Pyridine 1.3 1.4
 From a production perspective, there are some advantages to dispersing the selective adsorbent material
 From a reading of the above, one with ordinary skill in the art should be able to devise variations to the inventive features. For example, the filter plug, the general adsorbent section, and the selective adsorbent section may vary in length and diameter, relative to any dimensions specified herein and relative to each other. Further, the various section dimensions may be optimized for a particular tobacco blend or for particular tobacco rod dimensions. These and other variations are believed to fall within the spirit and scope of the attached claims.