Reduction of polycyclic aromatic hydrocarbons in tobacco smoke using palladium salts

Abstract

Methods for treating tobacco which result in the reduction of selected compounds from the tobacco smoke, and corresponding smoking articles containing this treated tobacco, are disclosed. In these methods, a solution containing a palladium salt is applied to the tobacco, preferably by spraying. The palladium salt preferably contains nitrate, chloride, acetate, citrate, gluconate, or salicylate as the anion. After application of the solution, the tobacco is preferably dried in an oven, by forced air, or by natural evaporation. The palladium in the treated tobacco results in the reduction in the level of polycyclic aromatic hydrocarbons, especially benzo(a)pyrene, from the total particulate matter in mainstream and sidestream smoke of the treated tobacco. The addition of mannitol and/or urea to the tobacco, and introduction of ventilation in a cigarette containing the treated tobacco, enhance the ability of palladium to reduce the level of polycyclic aromatic hydrocarbons in the smoke.

1 . A method for preparing tobacco comprising adding to tobacco a solution containing a palladium salt.  
   
   
       2 . The method of  claim 1 , wherein the anion of the palladium salt is nitrate, chloride, or the anion of an organic acid.  
   
   
       3 . The method of  claim 2 , wherein the anion of the organic acid is acetate, citrate, gluconate, or salicylate.  
   
   
       4 . The method of  claim 1 , wherein the solvent in the solution is water, acetone, ethanol, a mixture of water and acetone, or a mixture of water and ethanol.  
   
   
       5 . The method of  claim 4 , wherein the concentration of acetone in the mixture of water and acetone is from 5% to 15% (v/v), and wherein the concentration of ethanol in the mixture of water and ethanol is from 5% to 15% (v/v).  
   
   
       6 . The method of  claim 1 , wherein the concentration of palladium in the prepared tobacco is from 0.01% to 0.2% (w/w).  
   
   
       7 . The method of  claim 1 , wherein the concentration of palladium in the prepared tobacco is from 0.02% to 0.07% (w/w).  
   
   
       8 . The method of  claim 1 , wherein the solution further contains mannitol.  
   
   
       9 . The method of  claim 8 , wherein the concentration of mannitol in the prepared tobacco is from 0.5% to 20% (w/w).  
   
   
       10 . The method of  claim 8 , wherein the concentration of mannitol in the prepared tobacco is from 8% to 12% (w/w).  
   
   
       11 . The method of  claim 1 , wherein the solution further contains urea.  
   
   
       12 . The method of  claim 11 , wherein the concentration of urea in the prepared tobacco is from 0.5% to 10% (w/w).  
   
   
       13 . The method of  claim 11 , wherein the concentration of urea in the prepared tobacco is from 2% to 5% (w/w).  
   
   
       14 . The method of  claim 1 , wherein the solution contains mannitol and urea.  
   
   
       15 . The method of  claim 1 , wherein the weight of the solution added to the tobacco divided by the weight of the tobacco to which the solution is added is from 0.2 to 1.0.  
   
   
       16 . The method of  claim 1 , wherein the weight of the solution added to the tobacco divided by the weight of the tobacco to which the solution is added is from 0.4 to 0.9.  
   
   
       17 . The method of  claim 1 , wherein the weight of the solution added to the tobacco divided by the weight of the tobacco to which the solution is added is from 0.6 to 0.9.  
   
   
       18 . The method of  claim 1 , wherein the solution is added to the tobacco by spraying.  
   
   
       19 . The method of  claim 1  further comprising drying the tobacco after adding the solution to the tobacco.  
   
   
       20 . The method of  claim 19 , wherein the drying is done by forced air or natural evaporation.  
   
   
       21 . The method of  claim 19 , wherein the drying is done by forced air, and wherein the forced air has a relative humidity of from 50% to 70%.  
   
   
       22 . The method of  claim 19 , wherein a finite period of time is allowed to elapse between adding the solution to the tobacco and drying the tobacco.  
   
   
       23 . The method of  claim 22 , wherein the finite period of time is from 5 minutes to 24 hours.  
   
   
       24 . The method of  claim 22 , wherein the finite period of time is from 15 minutes to 3 hours.  
   
   
       25 . The method of  claim 22 , wherein the finite period of time is from 15 minutes to 1.5 hours.  
   
   
       26 . The method of  claim 22 , wherein the finite period of time is from 30 minutes to one hour.  
   
   
       27 . The method of  claim 1  further comprising making a smoking article containing the prepared tobacco.  
   
   
       28 . The method of  claim 27 , wherein the smoking article is a cigarette.  
   
   
       29 . The method of  claim 28 , wherein the cigarette contains a cigarette paper.  
   
   
       30 . The method of  claim 29  further comprising introducing ventilation holes in the cigarette paper.  
   
   
       31 . The method of  claim 29 , wherein the cigarette contains a filter, and the method further comprises introducing ventilation holes in the cigarette paper or the filter.  
   
   
       32 . Tobacco prepared by the method of  claim 1 .  
   
   
       33 . A smoking article containing the tobacco of  claim 32 .  
   
   
       34 . The smoking article of  claim 33 , wherein the smoking article is a cigarette.  
   
   
       35 . The smoking article of  claim 33 , wherein the cigarette contains a cigarette paper.  
   
   
       36 . The smoking article of  claim 35 , wherein the cigarette paper contains ventilation holes.  
   
   
       37 . The smoking article of  claim 35 , wherein the cigarette contains a filter, and wherein the cigarette paper or the filter contains ventilation holes.