Some Components of the Gas Phase of Cigarette Smoke ROGER 1. PHlLlPPE and MARCUS E. HOBBS N. C.
D u k e University, Durham,
The analysis of the g a s phase of cigarette smoke by application of an infrared absorption compensation technique has been extended to cigarette smoke from two additional tobacco compositions. Compounds identified and quantitatively determined that were not reported previously include butane, isobutylene, benzene, toluene, furan, and 2-methylfuran. A table lists the most useful absorption bands for the compounds identified, and several absorption bands for substances not yet identified are discussed. The differences observed in the concentrations of several constituents are discussed on the basis of the different types of tobaccos investigated.
E
S T E X S I O S of previous studies of the gas phase of cigarette smoke to two additional tobacco compositions-a blend of 50% cased burley-50% bright and turkish tobacco sampleswas desirable to supplement data previously reported (2f). The results reported in the present paper and the previous one (81) essentially complete the authors’ study of the gas phase of smoke from cigarettes made from the chief types of cigarette tobaccos. I t is felt that with the exception of some saturated hydrocarbons and possibly a heterocyclic compound as yet unidentified, the major components of the gas phase have been qualitatively and quantitatively established. There remains a considerable number of minor constituents on which further study could be ninde, but pursuit of such a program will require rather large numbers of cigarettes as a sample and would ad-
visedly make use of more effective methods of fractionation than have been used in the present or previous studies. The LeRoy distilling column (19) and gas chromatography (14-16) hold considerably more promise in this respect than the method used in the present investigation, nhich employs trap-to-trap type of distillation. APPARATUS AND EXPERIRIENTAL PROCEDURES
The apparatus and experimental procedures required for this study have been described (81) and in the present investigation all experimental variables such as puffing time, puff volume, cigarette weight tolerances, conditioning procedures, etc., were made to conform as nearly as was practicable to conditions previously used. One point of difference resulted from the use of a different syringe in the present work. The average volume per puff was approximately 30.8 cc. a t room temperature and pressui? rather than the 35 cc. per puff used in the previous work. This accounts for a puff volume a t normal pressure and temperature of approximately 34 cc. in the present work as recorded in Table I in contrast to approximately 32 cc. in previously reported data. The results, using infrared absorption measurement, of the analysis of the gas phase of smoke from cigarettes made from bright, burley, cased burley, and a blend of 50% bright-50wo burley tobaccos were given in the previous paper (21). The same procedure was used in the present investigation for the analysis of the gas phase of the smoke from cigarettes made from a blend of 507, bright-50% cased burley (10% destrose) and from turkish tobaccos.
A sample spectrum obtained on the model 21 Perkin-Elmer instrument, using a sodium chloride prism, shows the essential features of the method used (Figure 1). I n Figure 1 the compensated blank, or upper tmre, shon s diglit overcompensation.
-0 1
COMPEN S A T E D
E L A NK
80-
-
100
w
Bo
z 4 c
t 60 7
4
a c
5
40
U 0:
w a
20
4
,
I
6
I
L
I
I
8
MICRONS
I
,
10
Figure 1. Sample spectrum of condensable fraction collected at -154’ C. from gas phase of smoke of sixty 50% bright4070 cased burley cigarettes Showing absorption bands for constituents present, cell blank, and blank after compensation
2002
V O L U M E 28, NO. 12, D E C E M B E R 1 9 5 6
2003
Summary of Analyses by Infrared Methods of Gas Phase of Cigarette Smoke
Table I.
Component
co2
co
CH4 Ethane Propane Butane Propane butane Ethylene Propylene Acetylene Isoprene Butadiene Acetaldehvde Acetone Methyl ethyl ketone Methanol HCK Diacetyl
+
cos
Mole % ' of Total Volume, Cc./Puff a t N P T Blend 50% brightBlend 50% bright50% cased burley Turkish 50% cased burley 3.0 2.5 8.7 1.4 0.95 4.2 2 2 . 0 X 10 1 1 6 . 0 X 10-2 0.64 4 . 1 X 10-2 3 . 2 X 10-2 1 2 . 0 X 10-2 1 . 6 X 10-2 .... 4 . 7 x 10-2 0 . 2 x 10-2 0 . 5 x 10-2 2 . 5 " X 10-2 1 . 8 X 10-2 2 3 " X 10-1 6 . 8 " X 10-2 2 . 0 x 10-2 0 . 7 4 X 10-2 0 . 6 8 X 10-1 0 . 3 3 x 10-2 0 . 3 8 X 10-2 1 . 1 x 10-2 9 . 2 x 10-2 4 8 x 10-2 3 . 1 X 10-2 0 . 1 7 x 10-2 0.18 X 10-2 0 . 5 x lo-: 3 . 9 x 10-2 28.3 X 109 . 7 x 10-2 1 . 4 X 10-2 1 . 1 x 10-2 4 . 1 X 10-2 0.18 X 10-2 0 08 X 10-2 0.5 X 2 . 2 x 10-2 2 . 5 x lo-; 0 85 X 10-2 0 . 2 6 x 10-2 1 1 . 2 x 103 . 8 X 10-2 0 . 0 9 x 10-2 0 . 0 9 x 10-2 0 . 3 X 10-2 0 23 X 10-2 0 . 0 7 x 10-2 0 . 2 x 10-2 1 . 6 X 10-2 9 . 3 x 10-2 3 . 2 X 10-2 0 . 2 6 x 10-2 0 . 2 x 10-2 0 . 0 7 x 10-2 0 . 1 5 x 10-2 0 . 1 1 x 10-2 0 . 4 X 10-2 0 . 1 5 X 10-2 0 . 0 4 x 10-2 0 . 1 x 10-2 0 08 X 10-2 0 . 3 X 10-2 0 . 1 1 x 10-2 -0 11 X 10-Zb 0 . 0 2 x 10-2 - 0 . 3 X 10-2b 2 7 8 3 9.7 0 4 0.9 0 3 3.i 10.6 3 6 31 2 89.4 30 6 34.3 34 1
Gas Phase Turkish 7.3 2.8 0 47 9 . 3 x 10-2
....
7 . 2 " X 10-2 5.4 x 10-2 2 . 2 x 10-2
1 . 0 x 10-2 1 4 . t X 10-2
0 . a x 10-2 1 1 . 3 X 10-2 3 1 x 10-2 0 . 2 x 10-2 6.5 x 10-2 0 . 8 X 10-2 0 . 3 X 10-2 0.7 X 10-2 4.7 x 10-2 0.8 X 10-2 0 . 3 X 10-2 0 . 5 x 10-2 0 . 2 x 10-2 0 . 0 7 X 10-2 8.0 1 2 8.2 90.8
Methyl chloride IsobutyleneQ Benzene Toluene Furan 2-Methylfuran Condensed phase analyzedc Condensed phase not analyzedd Total condensables Total noncondensables Total volume ( X P T ) Average of mass spectral analyses of infrared inactive constituents (mole C r ) . Air -57°C ( 1 3 $ ) Nitrogen (excess) -24% (i 1c ~ ) Hydrogen 1 6% Argon 0 3% a Isobutylene was previously determined for cigarettes made from bright and burley tobaccos. The,mole 70 concentrations a-ere, respectively, 0.6 X 10-2 and 0.7 X 10-2. This compound was not determined for cigarettes made from cased burley and from 50% bright-50% burley tobaccos. b Estimated directly from spectrum. C Sum of volumes in cc.(puff a t N P T and of mole % of condensables quantitatively accounted for. Essentially all CO and CHI were obtained in noncondensable fraction. d Based on mass spectral analysis, this material consists of approximately 80 mole % water a n d 20 mole % of other constituents, including methanol and acetone.
--
In the regions betneen 3.2 and 3.3 microns near 6.9 and betLYeen 10.0 and 11.0 microns, the overcompensation resulted from impurities in the sample of ethane used for compensation. The ethane sample analyzed 95% of ethane with the remainder essrntially ethylene. Slight overcompensation near 3.4 and 6.8, 4 3 and 15, and near 4.9 microns is due to ethane, carbon dioxide, arid carbonyl sulfide, respectively. 4 small amount of uncomycnsated methane shows near 7.7 microns. The apparent underc-ompensation in the region of 7.4 microns is attributable to impiirities on the cell window. as may he seen from the cell blank trace. The gas phase of smoke obtained from sixty regular size cigarettes, TO mm. long, was used for the analysis of the condensable fraction. For the analysis of the blend, six fractions were col-100°, lected a t temperatures of -154O, -141", -125', -GO", and -20' C. The condensable gas phase of turkish cigarette smoke vias separated into eight fractions collected a t temperatures of - l G O " , -140", -loo", -go", -60", -40", -25", mid - 15" C . The noncondensable fraction of the gas phase in t h e present investigation 4 as analyzed by the procedure descwbed (21). RESULTS AYD DISCUSSION
Table I gives a summary of the analyses. I t is seen by comparison with the previously reported data (21) that some components i n addition to those previouslj- reported were identified and quantitatively determined: benzene, toluene, furan, and 2-methylfuvan. Isobutylene was also determined on the new s:imples and had been determined on some of the samples previously reported, hut was not included in the published data. Butane was identified, but it was rather difficult to estimate quantitatively because of the similarity of the useful absorption bands of ethane and propane. The figures for butane obtained for cig-
arettes made from the blend are given separately, but for turkish cigarettes, because the spectra did not allow one to distinguish between propane and butane, the results are given for the mixture of the two hydrocarbons. This difficulty is general for the saturated hydrocarbons containing more than three carbon atoms, and more efficient fractionation and identification techniques such as vapor chromatography are very desirable in this connection. I n addition to the difficulties experienced with the saturated hydrocarbons, there are some compounds, hydrogen sulfide for example, which may be present in the gas phase but which might not be detected at low Concentrations by infrared absorption technique because of rather low absorptivity. The characteristic absorption bands for benzene, furan, and 2-methylfuran were present in the spectra of the gas phase of smoke from tobaccos previously studied, but these compounds were not definitely identified a t the time. In the present investigation toluene was identified in the fraction collected a t approximately -20" C. and had not been found in previous work because the fractionation was carried only t o -50" C. I n the identification phase of this n-ork, it was most useful to run reference spectra of pure gases or vapors a t different pressures to locate the strongest and most specific absorption bands. The choice of an absorption band suitable for compensation depends, of course, on the partial pressure of the constituent in the specific mixture to be analyzed. For the components idrntified and quantitatively determined in the gas phase of cigarette smoke, the most useful absorption bands are listed in Table I1 along with the relative intensities and the absorption frequency values quoted from other authors. This table, by no means complete, is presented only as a norking tool to facilitate identification of the components and selection of suitable bands for compensation. The agreement a i t h other authors is generally good, except for a few cases such as carbon dioxide at 4.32 microns. In this case, the lack of agreement is primarily attributable to the accentuation
A N A L Y T I C A L CHEMISTRY
2004
~~
Table 11. Band Location and Identification A , lr (i0.01 p)
;:%} 2.73
", Cm.3 3717'~ 36101 3663
$::}doublet 3.18 3.24
3145 3086
3.26
3067
Cm.-' (Other Authors) 37161 3605: 3682 3683 3312.0 3312.9 3120 3085 v,
3053 3086 3020
Relative Intensity
Component
S.
Carbon dioxide
V.S.
Methanol
S.
Hydrogen cyanide
s.
Ethylene Isoprene Ethylene Butadiene, 1.3
3.
9.
3.32
3012
3.34
2594
3019.6 3020.3
\..s.
Ethylene Nethane
3.35
2985
2565
S.
Isoprene
3.37
2967
2555
::::)doublet
32);:
3.40
2541
2966.2 2967 2568.0
3.43
2515
S.
Butadiene, 1,3
V.S.
2804 2855
V.S.
+
Methanol
," :;]doublet
iii;!
9.00 5.68
1111 1033
2844 2843
v.3.
Methanol
3.70
2703
2704 2710 2345 3 2350 2146 ' 2116 7 ) 2079 2030 51
S.
Acetaldeliyde
10 53
992.1 545.7
10.97 11.02
511.6 907.4
Acetaldehyde
11.05 doublet 11.20) 11.25 12.63 13.37
505.0 892.9} 888.9 791.8 747.9
Acetone
13.45
743.5
Methyl ethyl ketone Diacetyl
13 67
731.5
V.S.
s.
Propylene
V.S.
+
m.
5.75
1739
5.80
1724
6.00' doublet 16671 6.10) 16391 5.23
1605
1647 16661 1642, 1608 16081 1597) 1603' 1587)
::;:}doublet
6.82
1760 17551 1725 1715
Carbon monoxide
V.S.
Carbonyl sulfide
S.
Butadiene, l , R
1466
1486 1463 1477 1470 1475 1462
v
s.
v.8.
+
10.08
Carbon dioxide
1828) 1812, 1764
1364
1170
2841
5.67
7 33
8.55
3.52
1821' 1812)
1376
Ethane
Butane
2: :;}doublet ~~~~) g: ::}doublet ;@:)
7.2i
1215
S.
;;f;j
1408
8.23
2916
$:;:}doublet
7 10
Propane Butane
288'7
2313
Cm.-1 1443
1355 1304
3.47
4.32
pj
7.36 7.67
3Iethyl chloride
S.
P
(iO.01 6 53
S.
Isoprene
3.
Butadiene, 1.3
V.S.
Ethane Propane Butane
of the 4.32-micron band a t the partial pressures of carbon dioxide encountered in these investigations. The data recorded in columns 1 and 2 of Table TI have not been corrected to vacuum, shereas most of the data recorded in column 3 are corrected values. This accounts for some of the discrepancies observed and in other cases the data in columns 1 and 2 give the doublet, whereas the literature values may be for the unresolved band or for the band center. Some authors give the values for the P and R branches-for example, furan a t 725 and 763 em.-'. The authors' value is for the Q branch and agrees well with the average of 744 em.-' for the P and R branches given in the literature. The instrument used in their work was calibrated using atmospheric water vapor, carbon dioxide, and polystyrene film
y, Cm.-i (Other Authors (3) 1440
1443 1445 1445 1405 1414 1375 1364 1354 9 1370 1373 1363 1388
(4) (1)
(6) (86) (POI
Relative Intensity
Component Etlislene Propylene Isobutylene Isoprene Acetaldehyde
(17) (7)
Propane
(17)
Meths1 chloride Acetaldehyde
(26) (20) (83) (26)
1306 2 1305 1202 1221
(23) (96)
1114 1121
(251 120)
1033.5 1034.2 991.1 549.2 950 550 910.7
(I;) (27)
909 508.7 509 505.8' 852.5] 890
(24) (6) (2)
748 747 725 763 732.1 732.3
(17) (7)
(Zz)
Acetone Methyl ethyl ketone Diacetjl Hydrogen cyanide Methane
(8,) Acetone bIeth31 ethyl ketone
(6)
(17) (97)
.kcetaldehyde Diacetyl Nethano1 Isoprene Ethylene
(3)
(4)
(6) (1)
Propylene Butadiene, 1 , 3
Isoprene Isobutylene 2-Methylfuran Propane
($2) (22)
Furan
(17) (27)
Methyl chloride
13.71
729.4
;p
I;{
13.73 13.78 13.90
728.0 725.7 719.4
730
(10)
720.5 720.9
(17) (97)
14.03
712.8
14.43 14.88
653.0 672 0
;;;:: I;[
Acetylene Toluene 2-Methylfuran Carbon dioxide Hydrogen cyanide
Toluene 654 (10) Benzene 071 (17) 671 (9) Carbon dioxide 14.97 661.5 667.3 (171 667 5 (67) Relative band strengths. v . 6 . very strong ( + indicates stronger of two very strong bands for same substance); s. strong; m. moderate.
over the range from 2 to 15 microns. The maximum deviation from correct values found over this lange was 10.015 micron and in general the deviations s e r e less than 3~0.01micron. Several absorption bands are not yet identified. First, some strong bands occurring in the spectrum of -80" C. fractions are undoubtedly related to one or several saturated linear or branched hydrocarbons. As mentioned above, saturated hydrocarbons containing more than three carbon atoms, xhen examined a t l o a pressure and over the limited spectral range used, are not readily distinguishable by the infrared technique. Table 111 gives the location of the bands the authors believe t o be indicative of saturated hydrocarbons, along with the correlation given by Bellamy (13).
2005
V O L U M E 28, NO. 1 2 , D E C E M B E R 1 9 5 6 Table 111. A.
Sharp hands (strong)
Broad bands (strong)
Y
P
Ci
