1374
INDUSTRIAL AND ENGINEERING CHEMISTRY
in Figure 7 are in close agreement, over the entire concentration range. Figure 8 shows that in the case of a 1 t,o 1 mixture of toluene and and n-heptane in dimethyl phthalate the selectivity calculated from J factors over a range of temperatures from 100 t o 300" F. agrees well with experimentally determined values and that selectivities a t practical solubilities may br as IOU, as 509;;, of the ultimate selectivity- at infinit,e dilution. ACKNOWLEDGMENT
The author wishes to express his appreciation fCJr the able and willing cooperation of Kalter A. Dietz, who assisted i n ohtaining the experimental data presented in this paper.
Vol. 41, No. 7
LITERATURE CITED
(1) Fenske, 31.R., and Varterrssim, K. A4.,1 x 1 . ENG.CHEW.,29,. 270-7 (1937).
(2) Francis, Alfred, Ibid., 36,7ti4 (1944). (3) Gilliland, E. R . , Zhid., 32, 1220 (1940). (4) Hibshman, H. J.,I b X , 32,988--91 (1940). (5) Hunter, T. G., and Naph, A . W.,J . Sac. Chem. Ind., 53, 9 j T (1934). (6) Mair, B. J., Willingham, ('. B., and Anton, ,J. S . , ,I.Research S a f l . Buy. S t a n d a d s , 21, 599 11938). (7) Perry, J. H . , ed., "Chemical Engineer's Handbook." 2nd ed., xt. 1382, New P o r k a n d London, McGram-Hill Book Co.. 1941. RECEIVEDAugust 23, 1847. Prefented before the Division of Potroleurrl Chemistry a t t h e 1 1 1 t h h l w t i n e of t.he A-lrmncAPi CxsmcAI, SOCJI CTT. .\Tlant,il: City, S . .I.
osition of Cigaret THE GASEOUS PHASE JOHN B. FISHEL iiND J. F. HASKINS Ohio S t a t e Zhiaersity, Columbus, Ohio T h e components of cigaret smoke have been reported by a number of different investigators. Among the known constituents of the gaseous phase of the principal Bmolw stream are carbon monoxide, carbon dioxide, hydrogen sulfide, and hydrogen cyanide. In the present work an attempt was made to determine these constituents as accurately as possible under conditions simulating those of normal smoking. The amount of carbon monoxide is shown to be less than 4.3 m l . per cigaret. Carbon dioxide is present to the extent of 7.7oJ, by volume equivalent to 34 ml. per cigaret. Hydrogen sulfide is present as 0.0019% by volume of the gaseous phase and hydrogen cyanide was not detected. Acetylene was found in the cigaret smoke and the presence of other unsaturated hydrocarbons was indicated.
T
HE composition of toba,cco smoke is a matter of corisiderable
interest, particularly in view of its possible physiological effects. Investigations of the Constituents of the smoke have been report,ed principally in medical and pharmaceutical journals. Much of it has been qualitative in nature and only a small part, has been carried out under conditions similar t o normal smoking. The present work is an attempt t o determine as accurat,ely as possible the nature and amounts of t.he subst,ances present in the smoke, under condit'ions as like those of normal smoking as possible. This paper is concerned primarily with the constituents of the gaseous phase of the principal smoke strem-i.r., that part of the smoke drawn through the cigaret. THE SMOKING MACHINE
In order to collect amounts of cigaret smoke sufficient for analysis, a smoking machine IS necessary. This device should simulate, as closely as possible, the action of the average smokei. The machine used in this work is, except for minor changes, thcl same as that employed by Bradford, Harlan, and Hanmw (6): By a suitable arrangement of a water buret and a four-way valve actuated by a motor, vacuum is applied alternately to four oigarets in a manner very like the action of a smoker. Each cigaret is puffed for 2 seconds, once each minute, t o dra-ii 40 ml. of air through the cigaret. The resulting principal smoke stream i b led through a device which separates the nongaseous part (liquid or solid) of the smoke from the grrseous, which is then rondurted
through a train of absorbents, Under rioriiial conditions it is pub.sible to smoke about 200 cigarets in a n 8-hour day. The cigarets used are a standard brand provided by the company which sponsors the investigation. Kio attempts have been made to rontiur~ comparative tests on different brands of cigarets. GEh-ERAL CH4RhC'rEKISTICS O F SMOKE
It bas been recorded in several instances in the literature ard Lonfirmed in the authors' laboratory that the principal smokr btream- that drawn through the cigaret- -is generally acidir while the secondary smoke stream-formed a t the glowing cnd oi the cigaret-is alkaline. This suggests that the secondarj ytream may contain substances not found in the primary stream The present investigation, honeever, has been confined t o a n examination of the principal smoke stream s w A m m o N OF c o r 2 L o m A i , PARTICLES O F SMOKE FROM GASEOUS PHASE
Tobacco snioke consists of two distinct phases, a ga,seoua ph which includes such compounds as carbon dioxide, hydrogen sulfide, carbon monoxide, and other materials which are gaseous or have high vapor pressures at, ordinary temperatures, and a liquid phase which consists of particles, of rolloidal sizc, w h i c h w.re liquids or solids a t ordinary temperatures. In previous investigatioiis different methods have bceri used t u separate rhe phases. Bradford, Harlan, snd Hannier (6) collected the smoke in a large Bask and allowed it t o settle. Other investigators passed the smoke through solvents such as i:hloroform or through sulfuric acid. The sedimentation method appeared to be too slow and the use of solvents introduced new compounds into the gaseous phase. Sulfuric acid could remove some of the gaseous constituents. In this work a saLisfac1;or.v separatioii of the phases was acconiplished by drawing the smoke from each cigaret through a Pyrex tube, 3 cm. in diameter and 30 em. long, packed tn a, dcpt,h of 23 cam. with O.l%-inch, singlrxturn, Pyrex helices. EXAMINATION OF GASEOUS PHASE
DETERMINATIOK OF CARBO\DIOXIDE. Carbon dioxide wadetermined by passing the gaseous phase of the smoke through au adsorption train as desciihrd h y Foulk ( 7 ) . The train consisted I J f the fnlhwing parts:
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1949
A bubbler containing a saturated solution of silver sulfate in 1 to 1 sulfuric acid. T h e silver sulfate removes hydrochloric acid and hydrogen sulfide from the gas. A Midvale bulb filled with Drierite to remove moisture. A Midvale bulb filled with Ascarite to absorb t h e carbon dioxide. A Midvale bulb filled with Drierite to prevent entrance of moisture from the rear. The entire train and the machine itself were flushed by drawing through it the smoke of five cigarets. At the end of this time the weight of t h e Ascarite bulb wss recorded. T h e train was immediately reassembled and five more cigarets were smoked. This process was repeated until good check results were obtained: Determinationa
Average a
Conditions, P = 754 mm. and T
Carbon Dioxide Gram M1.
0,3043 =
170.95
Drierite in a Midvale bulb t o remove moisture. Ascarite i n a Midvale bulb t o remove carbon dioxide. A combustion tube 12 inches long and 0.75 inch in diameter containing a 4.50-inch plug of copper oxide wire, heated t o 310" C. by means of an electric furnace. Drierite in a Midvale tube t o collect any water formed. Ascarite in a Midvale bulb t o absorb the carbon dioxide formed. Mixed Ascarite and Drierite in a Midvale bulb to prevent absorption of moisture or carbon dioxide from the air. I n carrying out the determination the train was Rushed with the smoke from two cigarets, after which the Drierite and Ascarite bulbs following the combustion train were weighed and the actual determination was started. A single determination involved the smoking of five cigarets. Significant quantities of moisture were found in the Drierjte bulb, indicating t h a t some compound containing hydrogen was coming over with the gas. Insertion of additional Drierite bulbs in the train did not alter the amounts of water and carbon dioxide formed in the combustion. Results are given in t h e following table: Resulta
25' C.
T h e cigarets were smoked t o a 0.75-inch stump and each required 11 puffs or a total volume of 440 ml. of air. The volume per cent of carbon dioxide was calculated to be 7.7774, which represents about 34 ml. per cigaret. This value is high by the amount of carbon dioxide in the air itself. The latter averages 0.035% by volume, a value which is well within the experimental error of the analysis. The value is also subject to revision if other acidic constituents are found. DETERMINATION OF CARBON MONOXIDE.Published reports of the amount of carbon monoxide in cigaret smoke differ widely. Pontag (10) reported 41.0 ml. of carbon monoxide per gram or about 30 ml. per cigaret. This determination was made b y using palladium chloride and is therefore a measure of the reducing power of the smoke. Armstrong and Evans (2') used iodine pentoxide and reported 0.6 t o 0.9% carbon monoxide in the smoke, or about 2.6 to 4 ml. of carbon monoxide per cigaret. Baumberger ( 3 ) also used iodine pentoxide and reported a value of 8.3ml. per gram of tobacco, or approximately 6 ml. per cigaret, which could be increased considerably with an intensified rate of smoking. Hogen (4)found about 3 ml. per cigaret, and Marcelet (9) 26 t o 30 ml. per gram (about 20 ml. per cigaret). Saruta ( 1 1 )reported 44 ml. per cigaret but gave no data on the method of determination. Tsumara (16)says 13.4 to 34.6 ml. per cigaret while de Voogd ( 1 6 )reports 2.6 t o 3.2% carbon monoxide in the smoke, which is equivalent t o about 13 ml. per cigaret. I n general, the smoke from cigars appears to contain a much greater amount of carbon monoxide. Thomas (IS) however, published a n analysis of cigar smoke using a hemoglobin test showing 0.02 ml. of carbon monoxide per gram. The reasons for such variatioiis undoubtedly lie in the manner of analysis, in the methods of smoking, and in the care with which interfering substances are removed. Procedures based on the reducing power of carbon monoxide, such as the use of iodine pentoxide, or palladium chloride are subject t o suspicion unless other reducing substances are completdy removed or shown t o be absent. Determinations based on use of cuprous chloride are also subject to correction if acetylenic hydrocarbons are present. Several methods were tried in the present work, and the method finally decided on was to try to remove every carbon compound possible except carbon monoxide and then t o oxidize the latter with heated copper oxide and determine the resulting carbon dioxide. T h e absorption train for this determination was as follows:
A bubbler tube containing a Maturated solution of silver sulfate in 1to 1 sulfuric acid (to remove hydrochloric acid and hydrogen sulfide).
1375
1 2 3
a
HzO,
COZ, Gram 0.1042 0 1257 0.1128 0,1188 0.1154
Gram 0,0362 0,0407 0.0357 0.0381 0.0377
4 Average Conditions, P = 754 mm. and T
= 25O
I
C.
If it is assumed t h a t all t h e carbon dioxide is formed by oxidation of carbon monoxide-neglecting the hydrogen-this would represent approximately 13 ml. of carbon monoxide per cigaret or about 3.0% carbon monoxide in t h e smoke. I t would seem obvious, however, t h a t either hydrogen alone, or water vapor or some hydrogen-containing organic compound was present in t,he smoke, therefore, these results are not reliable. U S E OF A LIQUID AIR TRAP
I n the next series of experiments a bubbler tube containing concentrated sulfuric acid was inserted in the train, as the first absorbent, and a trap, cooled with liquid air, was placed just before the combustion tube. One hundred cigarets were smoked and the smoke was led through the complete train. After t h e 100 cigarets had been smoked it was observed t h a t a small amount of a white solid had collected in the trap. OCCURRENCE OF UNSATURATED HYDROCARBONS IN CIGARET SMOKE
I n order to obtain a n approximate ana!ysis of the material trapped out in the experiment described above, the machine was stopped, and the liquid air b a t h removed. The white solid in the trap was allowed t o melt and the resultant liquid was allowed t o boil away a little a t a time, through the combustion tube. After the boiling had slowed down the absorbents following the combustion tube were changed and a second fraction was permitted to volatilize through the combustion tube. Finally after again changing the absorption bulbs, the trap was warmed by a water bath and nitrogen was passed through it t o sweep out the remaining material. T h e results are given in t h e accompanying table: Fraction 1 2 3 Total, 100 cigarets Average, 5 oigarets
H20, Gram 0.0497 0.0738 0.0419 0.1654 0.0083
coz,
Gram 0.2394 0.0862 0,0325 0.3581 0.0179
Carbon to Hydrogen Ratio 1:l.O 1:4.2 1:6.3 1:2.3
...
These results appeared to indicate the presence of unsaturated hydrocarbons in the smoke, while the ratio first obtained suggested the presence of acetylene. T h e relatively high ratios of hydrogen to rarhon in the last part of the distillate could be ex-
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
1376
plained as being due to the presence of different hydrocarbons, or t o traces of moisture carried through the absorption tubes as a result of the rapid passage of the gas. However, the fact that most of the material volatilized considerably below the boiling point of water and the observation t h a t the trapped out material had a11 odor characteristic of unsaturated hydrocarbons such as butadiene suggest t h a t this material is largely hydrocarbon in nature. ANALYSISOF Gas PASSING THROCGH TRAP. During the latter part of the run in which the material described above was being collected, several analyses were made of the gas passing through the trap by determination of the amount of water and carbon dioxide formed on combustion. These analyses were made on the basis of five cigarets each. HzO,
Uncorrected average Blank Corrected average
Gram 0.017’5 0.0219 0.0181 0,0192 0,0104 0.0088
co
0.0685
(Based on Cod Gram 0.0436
0,1044 0.0801
0.0664 0.0.509
0.0843 0,0458 0.0386
0.0536 0.0291 0.0245
COZ, Gram
The blank on the above series was made by running the machine without any cigarets and drawing the air through the train including the trap and its contents, for the length of time corresponding to that required for five cigarets. If the carbon monoxide is calculated on the basis of the carbon dioxide in the corrected average without considering the hydrogen, this amount would represent about 4.3ml. of carbon monoxide per cigaret (at 75-1 mm. and 25‘ C.) or 0.98% carbon monoxide in the smoke. However, because the gas stream, laden with acetylene and other hydrocarbons, is swept fairly rapidly through the liquid air trap it would spem probable t h a t the trapping out of hydrocarbons was not complete and that the blank in a run would be larger than t h a t shown above. If one makes the assumption that the hydrocarbons carried over have the same average composition as the blank, the carbon dioxide attributable to carbon monoxide becomes zero. Thus i t would seem plausible t o set the amount of carbon monoxide in the smoke a s somewhat less than 4.3 ml. or 0.9Syo carbon monoxide in the smoke. CONFIRMATION O F PRESENCE OF ACETYLENIC
HYDKOC4RBONS
I n order t o confirm the presence of acetylene the liquid collected in the liquid air trap from the smoking of 25 cjgarets was allowed to volatilize through bubbler tubes containing ammoniacal cuprous chloride, according t o the method of Scheiter ( 1 2 ) . A red precipitate of copper acetylide was formed and the amount of acetylene calculated from the weight of acetylide corresponded t o 0.05 to 0.1 ml. acetylene per cigaret. I n a n attempt t o check the amount of acetylene present the method described by Altieri ( 1 ) was used. This method involves passing the gas through aIcoholic silver nitrate and titrating the liberated nitric acid. The volume of acetylene indicated by this test was about 0.05 ml. per cigaret. This quantity of acetyIene is not enough t o account for the differences observed when a liquid air trap is used. Analysis of the combustion figures before and after use of the air trap indicates that the material trapped out has a n average carbon-hydrogen ratio of about 1 t o 3. The significant data expressed as averages o n a five-cigaret basis are given in the folloming table: HzO,
Before use of trap With use of trap Difference
Gram 0.037’7 0.0192 0.0185
coz,
Gram 0.1154 0.0843 0.0311
Carbon t o Hydrogen Ratio 1:1.6 1:l.l 1:2.9
Vol. 41, No. 7
I t is believed, therefore, t h a t other hydrocarbons are present in the trapped out material and a further investigation is being made of t8heirnature. DETERMINATION O F HYDROGEN SULFIDE
The presence of traces of hydrogen sulfide in cigaret smoke has been reported by several investigators. The only quantitative statement the authors have been able t o find is t h a t of Wenusch (18)who reports 0.007% hydrogen sulfide in the smoke. The authors have attempted the determination of hydrogen sulfide b y three different methods: absorption by anhydrous copper sulfat’eon pumice; absorption by ammoniacal cadmium chloride; and absorption by zinc acetate solut,ion followed by reaction wit,h p-dimethylaminoaniline hydrochloride in presence of ferric chloride, t o produce methylene blue (8). The first’ two of these mothods proved impractical because the amounts involved arc so small. The third method gave excellent results which may be considered accurate since methylene blue is a sulfur-containing dye and the reaction is, therefore, specific. Results according to t’his test, which is a color comparison test, follow. Using a standard containing 0.000425 gram of hydrogen sulfide, 20 cigarets gave a value of 0.000236 gram of hydrogen sulfide (average of two runs). Using the same standard, 40 cigarets gave a value of 0.000478 gram of hydrogen sulfide. These values correspond to a weight, of 0.012 mg. per cigaret or a volume per cent of 0 . O C ~ l 9hydrogen ~~ sulfide in the smoke. DETERMIN4TIOK O F XIYDROGEN CYANIDE
The presence of traces of hydrogen cyanide in cigaret sniolre has been reported by Scholler (IS), Waser and Stahli ( I 7‘), and de Campos (6). The authors were unable, however, to detect thib compound by application of the Prussian blue test xvhich is the most sensitive specific method for hydrogen cyanide. It is possible though t h a t any hydrogen cyanide present may have been removed by the tar trap, as Scholler ( I S ) reported that the m e of cotton filters effectively filtered it out. LITERAT1;KE CITED
(1) Altieri, V. J., “Gas Analysis arid Testing of Gaseous Materiala,” p. 330, New YorkGas Assoc., 1945. ( 2 ) ALrmstrong, H. E., and Evans, E:. Ir,, Biit. M e d . J . , 1922, I,
992-3. (3) Baumberger, J. P., .J. Pharmucol. Exptl. Therap., 21, 23-57 (1923). (4) Bogen, Emil. J . Am. M e d . Sssoc., 93, 1110-14 (1929). (5) Bradford. J. A., Harlan, 151. R., and Hanmer, €1. R., IND.EXG. CHERI., 28, 836-9 (1936). ( 6 ) Campos, 11.. D. de, -492akS facultad farm. y odartol., Unio. SBo Paulo, 1, 15-24 (1939--40). (ij Foulk, C. W., Moyer, I-€. V., and MacNevin, W., “Introductory Note on Quantitative Analysis,” Columbus, Ohio, H. L. Hedrick, 1940. (8) Jacobs, M. R., “ h a l y t i c a l Chemistry of Industrial Poisons. Hazards, and Solvents,” second revised reprint, p. 258, Xew York, Interscience Publishers, 1944. ‘ (9) Marcelet, H., Bull. soc. chim. France, 3-4,556-8 (1908). (10) Pontag, J. J., 2. Untersuch. Xahr. Genussm., 6, 673-91 (1903). (11) Saruta, N., Hzikuoka Bcta M e d . , 31, 180 (1935). (12) Scheiter, 2 . anal. Chem., 48, 529 (1909). (13) Scholler, Rudolf, Chem. Zentr., 1939, 11, 1403. (14) Thomas, Ber. deut. pharm. Ges., 10,19-31 (1900). (15) Tsumara, H., J.Chosen N e d . Assoc., 27, 926-9 (1937). (16) Voogd, J. G. de, and Linden, 8 . van de, Het Gas, 59, 165-6 (1939). (17) Waser, E., a n d Stahli, A”,, 2. Unterszich. Lebensm., 67, 280-4 (1934). (18) Wenusch. A , , Ibid., 70, 201-4 (1935). XECEIVED January 30, 1948. A cooperative research contribution of the P. Lorillard Company and the Ohio State University Research Foundation.
