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-4- It was also decided that the filter should incorporate IOO mg of carbon which would be expected to reduce substantially (i) biological activity in those tests in which vapour phase constituents are known to be responsible for the major part of the activity and (ii) vapour phase components such as acrolein, formaldehyde, acetaldehyde and hydrogen cyanide. It was found impractical to make a "Dalmatian" type dual filter with a sufficiently high loading of carbon on the paper, so it was decided to employ a triple filter with the following specification: Houth Section I Carbon Section Tobacco Section I 7= I 6= 12~n i Cellulose Acetate ICarbon, i00 mg Jw Paper I Because equipment for manufacturing 25 ann triple filters was not available at the start of this work, quadruple filters (Filter No. l) were made as a substitute. These had a 7 mm cellulose acetate mouth section, a 5 n~ carbon bed and 6 * 7 mm paper sections. Due to the extra cutting involved the use of these substitute filters resulted in a small increase in draw resistance without a concomitant increase in filtration efficiency. Sutcliffe Speakman activated carbons (grades 203B and 205C) were considered because both appear to have a minimum adverse effect on taste (5). A Paramecium test gave a fractionally (but not significantly) better result for 205C and this carbon was used for the first filters. Because of difficulties in manufacture, possibly associated with the softness of this carbon, and because of a higher aldehyde efficiency, rxo rk9

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-5- 203B (20-50 mesh) was used in a second batch of filters. These were triple filters, conforming to the specification given on page 4, and are referred to in this report as Filter No. 2. Because the combined use of (i) a high efficiency filter and (ii) a tobacco diluent was expected to reduce i~act, it was decided to load the paper section of the Filter No. I with 10% sodium carbonate. This is known to increase impact (6). However, using these filters, it was found that impact was higher than from a typical U.S.K.S.F.T. cigarette, and sodium carbonate was omitted from Filter No. 2. The No. i filter was tested for TPM and nicotine filtration efficiencies when attached to 70 ~m cigarettes of blend 102. The results (Table I) showed that the filter had a satisfactory efficiency but a rather high pressure drop. Nevertheless, this quadruple filter was accepted as the best approximation to the target values available at the time and was used (with limited numbers of Filter No. 2) in the manufacture of the cigarettes described in this report. TABLE I PRESSURE DROP AND FILTRATION EFFICIENCIES OF FIRST BATCH OF FILTERS Property Pressure drop (cm W.G.) TPM Efficiency (%) Nicotine Efficiency (%) Target Actual 7 60 I0 62 5O 3. Cigarette Paper The delivery of cigarette smoke components may be reduced by increasing the quantity of secondary air drawn into the cigarette

-6- either in =he tobacco rod section or the filter, or both, by the use of highly porous or perforated cigarette paper or perforated plug wrap and =ipping paper. In the presen= work, it was decided to use a high porosity cigarette paper, at least for the first designs. Bollore 511C paper which contains 0.9% of sodium citrate was selected. Recent work has suggested that, for a given porosity, papers treated with citrate salts as burning accelerators produce a somewhat lower delivery of TPM than do either untreated papers or those containing other salts (7). The porosity of this paper (590 ml/min) is significantly higher than that (typically 260 ml/min) of papers used in commercial U.S.K.S.F.T. cigarettes, although citrate-treated papers are often used. 4. Tobacco Blend A tobacco blend was devised (8) bearing in mind =wo constraints: (i) It should be similar to that in a blended cigarette with respect to con=enC of flue-cured, Burley and Oriental tobaccos. (ii) It should have a nicotine content of 3%, because of anticipated dilution with non-tobacco materials. The blend used is given in Appendix I. A normal stem content equivalent to 20% of the tobacco blend was incorporated. Rather than import stem specially for the purpose, locally available stem was used. The expected TPM delivery from cigarettes made with 1OO% of this tobacco blend to the above specification was calculated using the Cigarette Design Handbook (9). These calculations (given in Appendix II) suggested that 100% tobacco cigarettes would have a TPM yield greater than lO mg, indicating the need to use tobacco diluents. CD r~D CO

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-7- 5. Tobacco Diluents The first requirement of any tobacco diluent in this application was that it should result in a final TPM delivery of not more than I0 mg per cigarette. Other considerations were (i) the effects on specific biological activity, (ii) effects on carbon monoxide delivery, and ~iii) effects on acceptability. The tobacco diluents considered were: (i) Non-combustible filler (IO, ii). (ii) Cytrel 1-324 (12). (iii) PCL (Brown & ~illiamson, X-PCL-5). It was proposed to use these diluents as follows: Cigarette Tobacco A B C D 50 SO 50 50 PCL NCF 1-324 O 50 0 25 25 0 O O 50 25 O 25 The anticipated reductions in TPM delivery on using each of these three diluents are discussed later, in the section on smoke chemistry; the calculations are given in Appendix II. It should be noted that only the original high density NCF was available; lower density material could have been advantageous. The composition of the NCF used was 76% calcium carbonate, 7% SCMC, 15% E2E lamina extract and 2% glycerol.

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-8- B. Cigarette Manufacture After conditioning, the selected blends were cut at 30 c.p.i. The high density of NCF has already been found to require careful setting of the making machine (II) to avoid rejection as winnowings. This problem may be greater with tobacco cut at 30 c.p.i, than with tobacco cut at 60 c.p.i., and in making the first experimental cigarette (RAg2) from a 50:50 mixture of tobacco and NCF, more than half of the latter was rejected. When a second portion of this mixture was made into cigare=~es (RAgl), the making machine was re-set and rejected very little NCF. Five different tobacco rods were manufactured; for technical reasons, 69 nrn rods were made and then cut to 60 mm. Some of each of these five had the first filter attached, and some of one design (RA85) also had the second filter attached. The six different cigarettes produced were then as listed in Table 2. TABLE 2 COb~OSITION OF SIX EXPERIMENTAL K.S.F.T. BLENDED CIGAP~TTES Cigarette Design A B C D A D Code t iRA82 RA83 RA84 RA85 RA91 RAg5 Filter i I I i 1 2 Tobacco Rod, Weight % Composition Tobacco 78 50 &8 50 51 50 PCL NCF O 25 0 25 I 0 25 22* 25 0 0 49* O 1-324 O O 52* 25 o 25 Filter Additive on Paper Section Sodium Carbonate, 10% t! tt I! I# None Carbon 205C IV 11 I! I! 203B *These figures were determined by blend separatzon; see Appendix III. CID

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