Beitrage zur Tabakforschung International · Volume 12 · No. 2 · June 1983
DOI: 10.2478/cttr-2013-0525
The Effect of Some Nitrogenous Blend Components on
NO/NOx and HCN Levels in Mainstream and Sidestream Smoke*
by V. Nonnan, A. M. !brig, T. M. Larson and B. L. Moss
Lorillard Research Center, Greensboro, Nonh Carolina, U.S.A.
SUMMARY
Vapor phase NO concentrations in mainstream and sidestream smoke correlated well with blend nitrate levels
over the range from 0.07 to 3.70%. Native and added
nitrate fit the same corrdation. No measurable amounts
of NOt were detected in the vapor phase. When the
mainstream and sidestream data were extrapolated to
zero nitrate levd, there remained a large residual amount
of NO (approximately 100 j.lg/cig.) which could be
attributed neither to nitrate nor to other nitrogenous
blend components of the total volatile base type.
Nitrogen-free cellulose cigarettes yielded of the order
of SO 1-lg of NO per cigarette indicating that pan of the
residual NO probably arises from the oxidation of
atmospheric nitrogen. The paniculate phase contained
small but measurable levels of nitrate which, with the
exception of Mg(NOl) · 6 H 20 added cigarettes, did
not relate to blend nitrate levels. Mainstream vapor
phase HCN level correlated weakly with blend nitrate
levels but other nitrogenous materials whether native or
added showed no clearly defined precursor-product
relationship with smoke HCN yield. The partitioning
of HCN between the vapor and particulate phases was
not affected by any of the test variables.
ohachten. Stickstoffdioxid wurde in der Gasphase in
meBharen Mengen nicht gefunden. Wenn die fiir Hauptund Nehenstromrauch ennittelten Oaten auf einen Nitratgehalt von Null extrapoliert wurden, blieb eine
greBe Stickstoffmonoxidmenge iihrig (ungefahr 100 IJ.g
je Zigarette), die in der Tahakmischung weder auf Nitrat noch auf andere stickstoffhaltige Komponenten der
fli.ichtigen Basen zuriickfiihrbar war. Bei stickstofffreien
Zellulosezigaretten ergab sich eine Stickstoffmonoxidausbeute in der GrOBenordnung von SO llS je Zigarette,
woraus geschlossen werden kann, daB ein Teil des Stickstoffmonoxids wahrscheinlich von der Oxidation
atmospharischen Stickstoffs herriihrt. In der Panikelphase aufgefundene kleine, aber meBbare Nitratmengen
standen in keinem Zusammenhang mit dem Nitrat der
Tabakmischung; eine Ausnahme machten bier Zigaretten, denen Mg(N0 3) • 6 H 20 zugesetzt worden war.
Die Menge der in der Gasphase des Hauptstromrauches
befindlichen Blausiiure und der Nitratgehalt der Tabakmischung korrelierten schwach miteinander; andere
Stickstoffverbindungen, ob sie natiirlich vorhanden oder
zugesetzt worden waren, erwiesen sich hingegen nicht
eindeutig als Vorlaufer der im Rauch enthaltenen Blausaure. Die Verteilung der Blausaure zwischen Gas- und
Panikelphase wurde von keinem der Versuchsparameter
beeinflu6t.
ZUSAMMENFASSUNG
RESUME
Im Konzentrationshereich von 0,07 his 3,70 % zeigte
sich eine gute Korrelation zwischen dem Stickstoffmonoxidgehalt der Gasphase von Haupt- und Nehenstromrauch und dem Gehalt der Tahakmischung an Nitrat. Die Korrelation war sowohl hei im Tahak natiirlich vorhandenem wie hei zugesetztem Nitrat zu be-
* Presente<j,
in pan, at the }Sth Tobacco Chemiru' Researclt Conference at
Winston-Salem, North Carolina, U.S.A., in <ktober 1981.
Received: 27th April 1982 - accepted: Bib Much 1983.
Une benne correlation entre la teneur en monoxyde
d'azote de la phase gazeuse de la fumee des flux principal et secondaire, et la teneur en nitrate du melange,
s'est manifestee dans une zone de concentration allant de
. 0,07 a 3,70 %. On a observe cette correlation aussi bien
dans le tabac presentant naturellement du nitrate que
dans ceux auxquels il fut ajoute. On n'a pas pu detecter
de quantite mesurable de NOt dans la phase gazeuse.
En extrapolant les donnees mises en evidence pour le
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55
flux principal et le flux secondaire, a une teneur en nitrate de 0, il reste toutefois une grande quantite de
monoxyde d'azote (environ 100 llg par cigarette), que
l'on ne peut attribuer dans le melange ni au nitrate ni a
d'autres composants azmes de !'ensemble des bases
volatiles. On a observe sur les cigarettes de cellulose
exemptes d'azote, une quantite de monoxyde d'azote de
l'ordre de 50 llg par cigarette, ce qui permet de conclure
qu'une partie du monoxyde d'azote provient vraisemblablement de l'oxydation de !'azote atmospherique.
Les petites quantites de nitrate mesurables toutefois que
l'on a trouve dans la phase particulaire ne peuvent etre
rapprochees du nitrate contenu dans le melange de
tabac, a !'exception des cigarettes auxquelles on avait
ajoute du Mg(N03 ) • 6 H 20. On a observe une faible
correlation entre la quantite d'acide prussique contenu
dans la phase gazeuse de la fumee du flux principal et
la teneur en nitrate du melange. Par contre, les amres
produits azotis, qu'ils soient d'origine ou aient Cte
ajoutes, ne se sont pas nettement revetes comme precurseurs de l'acide prussique contenu dans la fumee. La
repartition de l'acide prussique entre les phases gazeuse
et particulaire, n'est influencee par aucun des paramftres
du test.
INTRODUCTION
Repeated investigations have shown nitric oxide (NO)
to be the major oxide of nitrogen in cigarette smoke
although minor amounts of nitrogen dioxide (NO.z)
(6, 10, 13) and nitrous oxide (N 20) (16) have also been
identified. Most of the NO in smoke arises from nitrate
in the leaf, especially from Burley and various air-cured
tobaccos. The extent of conversion of added 15NO,into NO, N 20 and HCN has been investigated by
Hardy and Hobbs (7). It has also been reported that
there is a substantial underlying NO level in smoke
which is not related to nitrate (17). Several other
reactions involving nitrate take place as well, most
notably the reduction to ammonia, and the subsequent
formation of various nitrogenous products as reported
by ]ohnson and eo-workers in some 15N experiments (8).
Generally, when inorganic nitrates decompose thermally, the reactions leading to the formation of
nitrogen oxides proceed as shown in Figure 1. Heavy
metal nitrates decompose thermally forming N0 2 ,
whereas light metal nitrates go through a nitrite step
and eventually form NO. An acidic, reducing medium,
in particular, promotes the formation of NO. The conditions in a burning cigarette would thus favor the
formation of NO since the major cations present are K,
Ca, Na and Mg, and the environment is reducing and
acidic.
Once NO is formed and proceeds down the tobacco
column, it comes in contact with successively more
oxygen which diffuses into the cigarette through the
paper. Some N0 2 can be generated by the termolecular
reaction between oxygen and NO since the oxygen level
56
Figure 1.
nitrates.
Thermal decomposition reactions of metal
Ughtmerals
2 MN03 13MN02 -
2 MN02 + 02
JM20 + 7MN03+ 2NO+ 2·N2
Heavy metals
2M(N03)2- 2M0+4N02 +02
2 N02 + H:P 2 HN02 + H20 -
HNOs + HN02
HN03 + NO+ H30+
In acidic, reducing environment
N02- +A-+ 2H30+- .NO+A + 3H 20
increases from approximately 1% immediately behind
the burning cone to about 12% at the exit, especially
during the initial puffs (11, 12).
Figure 2 illustrates the oxidation rate of NO under
typical conditions within a cigarette (30 llg NO/puff
and ol (10%) (v/v)). This plot shows the rate of disappearance of NO with a rate constant of 7.12 X 109
cm6 mol- 2 s- 2 (2). Clearly, during a two-Second puff
there is little chance for an appreciable amount of
oxidation to take place, but in a period of one minute
about 5% of the NO could react. Thus, if there is a
significant amount of dead volume in the apparatus,
a measurable amount of artifactual N0 2 can arise.
N0 2 reacts readily with water, disproportionating into
HN03 and HN0 2• One eventual end product of these
reactions is nitrate which would show up in the particulate phase and should be most prevalent in smoke
from high nitrate level cigarettes.
Hydrogen cyanide is predominantly formed from pro·
teinic and amino acid precursors but there have been
some indications that the total pool of nitrogenous
materials in tobacco may contribute to the HCN level
in smoke as well (14).
In the current investigation, the relationships between
the nitrate level in the blend (natural as well as added)
and the mainstream and sidestream yields of nitrogen
oxides. and HCN were examined for both the vapor
phase anci the particulate phase. Also investigated was
the effect of some other nitrogenous blend components
and additives on the NOI and HCN yields in smoke.
MATERIALS AND EXPERIMENTAL
Four series of 84 mm filter cigarettes with 20 mm cellulose acetate filters and 25 mm non-porous tipping were
prepared. All these cigarettes used a commercial cigaUnauthenticated
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Figure 2.
25
"0
Q>
N
NO
+ NO + 02-+ N02 + N02
d[NO]
- - - = k [NO] 2 [02]
0
z
Rate of disappearance of NO.
dt
20
at298 K
k = 7.12 x 109 cm 6 mol- 2 s- 2
'5
';(
0
15
[NOl = 30 llQ/puff
0
Q>
Cl
.!!!
"'~
[0 2] = 10% (v/v)
10
Q>
0..
5
0.2
2
0.5
Time
3
4
567
(min)
rette paper with a Coresta* air permeability of
18.6 cm 3 min-t cbar- 1 (10 cm 2 test area) and a 0.85%
citrate content.
The first series was a. flue-cured grade with increasing
proportions of Mg(N0 3) 2 • 6 H 20. This salt lowers
smoke pH but does-not affect burn rate significantly.
The second series comprised blends of a single fluecured grade with a high nitrate Burley grade. Increasing
the Burley leads to substantial increases in smoke pH
and burn rate.
The third series was a selection of flue-cured grades of
different total volatile base (TVB) levels, and the fourth
one a flue-cured grade with different nitrogenous compounds added to increase the TVB level.
Finally, an all-cellulose control cigarette was handprepared to provide a standard with no nitrogenous
components. Nitrogen oxides in the gas phase were
analyzed with a Beckman 951 chemiluminescent analyzer. Nitrate content of the particulate phase was
determined with a nitrate ion electrode (15). The HCN
analysis was based on a previously published colorimetric AutoAnalyzer method (5). The analytical
precision for the nitrate electrode, chemiluminescent
analyzer and HCN determination are in the range of
10 percent.
The sidestream collection scheme used m the
NO/N0 2 /N0 3- analysis is shown in Figure 3. The
sidestream smoking chamber had a volume of 280 cm3
and was similar in design to that described by
Brunnemann and Hoffmann (3). An air flow rate of
17.5 cm3 Is was found to be necessary to maintain the
requisite burn rate and obtain the same number of puffs
as in standard smoking. The particulate phase was collected on a Cambridge pad and the gases from the sidestream were sampled with another smoking machine
puffing at the rate of four 35 cm3 two-second puffs per
minute. The 35 cm3 aliquots of sidestream were injected
Figure 3.
Sldestream sampling apparatus.
Chemilumi'nescent analyzer,
pump
t-------
3500 cm 3 /min
L_
L.!:::::===:;-"il
35 cm 3 2-second puff
per 15 seconds
r====---t__
Lighter
35 cm 3 2-second puff
~ perminute·
Flowmeter
(1050 cm 3 /min)
•• Cooperation Centre for Scientific Research relative to Tobacco, Paris.
Unauthenticated
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57
00
1.11
Total
volatile
bases
(%)
0.67
No3-
No3-
No3-
No3-
+ o.5%
+ 1.o%
+ 2.o%
+ 4.0%
0.34
0.35
0.35
0.36
0.37
12
12
12
12
13
Puff
number
0.72
2.70
Butley
8
492
460
2.30
Blend 3
8.5
0.58
1.11
9.5
Blend 2
337
10
185
168
0.46
13
959
569
371
213
168
I
23
30
17
61
31
17
particulate
phase
Mainstream
(MS)
vapor
phase
0.49
0.46
Blend 1
0.37
0.07
Control
flue-cured
Flue-cured and Burley blends (native N03 -)
3.67
1.85
1.03
0.07
Control
flue-cured
Flue-cured and added Mg(NO:J 2 • 6 H20
(%)
No3-
NO
Table 1.
2677
2494
1810
4386
2896
1810
vapor
phase
I
2
1
22
23
20
22
particulate
phase
Sidestream
(SS)
(Jlg/cigarette)
5.2
6.8
9.9
4.3
7.3
9.9
SS/MS
(total)
NO and HCN yields In smoke.
99
198
166
400
208
186
139
166
vapor
phase
I
53
76
80
55
67
70
53
80
particulate
phase
Mainstream
(MS)
46
49
97
95
111
97
vapor
phase
I
7
10
11
6
14
11
particulate
phase
Sidestream
(SS)
(llg/cigarette)
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HCN
0.35
0.22
0.44
0.22
0.49
. 0.44
SS/MS
(total)
into a 3500 cm3 /min air stream flowing through the
chemiluminescent analyzer. For HCN analysis, the
total sidestream was collected with an impinger trap
fitted with a coarse fritted glass bubbler and containing
30 cm3 0.126 N NaOH.
RESULTS AND DISCUSSION
A typical tracing of NO concentration as shown in
Figure 4 illustrates the rate of NO generation during
the 2-second puff and 58-second static bum cycle.
Apparently, the concentration is at a minimum during
the puff, reaches a maximum midway between puffs
and diminishes towards the end of the puff interval.
These . observations were surprising and prompted an
evaluation of the effect of dead volume between the
cigarette and the sidestream sampling syringe. Injecting
dilute NO into the smoking chamber and sampling over
different time intervals, indicated that most of the nitric
oxide was transferred almost immediately to the sampling syringe with a minor and diminishing portion
tailing for at least ten seconds. Thus, the dead volume
behaved as a buffer and tended to provide a time
averaging effect without obscuring the relative relationship between the instantaneous levels.
Intuitively, one would expect the NO generation rate
to be highest immediately after the puff while the cone
is elongated and the apex of the cone is being consumed
at its fastest rate. The initial low NO concentration
probably indicates that some of the nitrate in the cone
apex had decomposed during the previous puff.
The NO and HCN yields for the flue-cured tobacco
with added Mg(N0 3h · 6 H 20 and the native nitrate
series are shown in Table 1.
Vapor phase NO yields for both mainstream (MS) and
sidestream {SS) correlate well with blend nitrate level.
The particulate phase levels, although determined as
N0 3 - are expressed as equivalent quantities of NO.
Except for the MS in the flue-cured plus Mg(N0 3)2
series, the particulate phase yields do not correlate with
blend nitrate levels.
When the chemiluminescent analyzer was used in the
NOx mode, no significant quantity of N0 2 was found
in either the MS or the SS smoke.
Figure 5 depicts the per cigarette MS vapor phase NO
yield as a function of blend nitrate content. The added
and native nitrates have different slopes because the
bum rate of flue-cured/Burley blends changes, whereas
that of the added nitrate cigarettes remains constant.
Both relationships are linear and there is a large
intercept.
When the same data are expressed on a concentration
basis (i.e. on the per puff basis), all the points fall on
the same line as shown in Figure 6. On the per cigarette
basis, the flue-cured, added nitrate cigarettes contain
more tobacco and hence, yield more MS NO than
native nitrate cigarettes of equivalent N0 3- levels. On
the per puff basis, about the same amount of tobacco is
burned per puff and about an equivalent amount of NO
is delivered.
Figure 5.
phase.
Per cigarette yield of NO In mainstream vapor
1000
NO (IJg/cig.) =
229.5 (% added N03 -)
Figure 4.
NO concentration In sldestream (marks on the
baseline indicate puffs).
+ 121.5
r = 0.993
~
e<11
Cl
~
Cl
c:
~
0
""
~
500
0
z
CD
()
§
0
z
(%native N03 -)
puff
puff
0
Time
puff
puff
2
3
(min)
1.0
2.0
Blend N03 -
3.0
+ 155.9
4.0
(%)
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59
Figure 6.
phase.
80
Concentration of NO In mainstream vapor ·
0
A
Figure 8.
Conversion efficiency of N0 3- Into. NO.
added
native
~
s::::J
50
(';
c:
Q.
.....Cl
50
Ql
.::
~Ql
6
0
·e
z
(% N03 -) + 10.257
20
r = 0.9945
0.2
1.0
2.0
3.0
4.0
(%)
The total potential NO that a cigarette can yield is
calculated from the total nitrate in the tobacco column
smoked under standard smoking conditions (length
smoked = tipping plus 3 mm = 56 mm). The actual
yields were corrected for the zero nitrate intercept
values and the conversion efficiencies for the various
smoke fractions are based on the corrected yields. For
the corrected yields, the SS /MS ratio shows no correlation with blend nitrate since the ratio is erratic covering a range of 3.2 to 5.2. It seems intuitively obvious
that the ratio should be constant for the added nitrate
NO In sldestream vapor phase.
400
-300
·e.....c:
Cl
.::
200
0
z
100
A
0
3.0
2.0
Blend N03-
60
20
A
0
(%)
1.0
2.0
3.0
native
added
4.0
Percentage of N03 -
Figure 7 shows SS vapor phase NO yields on the concentration basis. As in the previous two plots, there is a
considerable amount of NO in smoke at an extrapolated zero blend content of nitrate. The NO delivery
for the zero nitrate cigarette is much higher for the
sidestream than for the mainstream and thus the SS /MS
ratio (total) decreases with increasing blend nitrate.
1.0
8
10
Blend N03 -
Figure 7.
Ql
>
native
added
4.0
series where the bum rate does not change, but it was
not clear, a priori, for Burley blend cigarettes where the
bum rate does change and hence, puff number is
different.
Some measurements were conducted on the length of
tobacco column burned during the puff and static bum
intervals. The all Burley and the all flue-cured control
represent two extreme cases which were examined in
detail. While the puff numbers varied from 8.0 to 13.0,
the ratio of paper length consumed on the tobacco
column during the static bum and puff intervals was 1.4
for both cigarettes. Further examination revealed that
the ratio of mass consumed was 2.2. The difference of
1.4 versus 2.2 arises from the predominance of peripheral burning during puffing; however, since both
methods gave the same ratios for Burley and bright
cigarettes, the ratio between the puff and static bum
intervals appears to be independent of bum rate. It
should be noted at this point that the NO vapor phase
SS /MS ratio was between 3 and 6 indicating that much
more NO goes into the sidestream than would be predicted from the respective amounts of tobacco consumed.
The conversion efficiency of nitrate into NO is shown
graphically in Figure 8. The conversion is rather efficient at very low blend nitrate contents, but drops off
drastically at the upper levels. Native and added nitrate
follow the same relationship.
The HCN analyses in Table 1 show a moderate increase
of vapor phase MS HCN level as a function of blend
nitrate content but neither the particulate phase MS nor
any of the SS analyses show any correlation. Generally,
the ratio of SS /MS is very low. This has been shown
before by several authors (4, 9). There is a considerable
range of smoke pH values involved from the acidic
Mg(N0 3)z · 6 H 20 cigarettes (pH = 4.5) to the all
Burley cigarette (pH = 7.2), but over this range the
partitioning of HCN between the vapor and particulate
phases is not affected (HCN Ka = 7.2 X 10- 10).
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Table 2.
No 3(%)
Potential
NO
(IJg/cig.)
Conversion efficiency of N03 - Into NO.
Mainstream (MS)
(%)
vapor
phase
I
particulate
phase
Sidestream (SS)
(%)
vapor
phase
I
particulate
phase
Total
(%)
SS/MS
Control
flue-cured
0.07
244
15.6
0.4
49.1
0
65.1
3.2
+ 1% Nos-
1.03
3730
6.7
0.4
32.3
0
39.4
4.8
+ 4% Nos-
3.67
14200
5.9
0.03
19.0
0
24.9
3.2
Blend 2
(native N03-)
1.11
3550
6.8
0.4
35.5
0
42.3
5.2
Burley
2.70
7600
5.4
0.08
21.5
0
26.9
4.0
Finally, a variety of nitrogenous materials were added
to a flue-cured blend at the 2 % level to determine
whether some other classes of compounds could be
potential precursors of NO. The results of these experiments are summarized in Table 3. There is no apparent relationship between native total volatile . base
content of tobacco and NO in smoke nor did any of the
added nitrogenous compounds produce significant
changes in the NO yield.
The observed significant level of NO in smoke at the
extrapolated zero blend nitrate level suggests the production of NO from atmospheric nitrogen or from
other nitrogenous sources in the blend that are different
from the compounds tested.
Table 3.
To test the atmospheric nitrogen hypothesis, some cigarettes were prepared by hand from nitrogen-free cellulose. These cigarettes delivered 50 J.tg of MS vapor phase
NO per cigarette, i.e. approximately half of the extrapolated zero nitrate tobacco cigarette value. The SS
vapor phase NO yield of the cellulose cigarette was of
the order of 15 J.tg/min (referring to the sc~e of Figure
7). Thus, the results suggest that some of the NO arises
from atmospheric nitrogen.
The variation of native TVB levels in tobacco has ·no
discernible effect on HCN yield. The various nitrogenous compounds which were added to the blend at
the 2% level showed variations in the HCN yield but
these may be largely related to the thermal stability of
NO and HCN (IJg/clgarette) mainstream yields (nitrogen sources other than N03/ .
No3-
(%)
Total
volatile
bases
(%)
Puff
number
NO
(vapor phase)
HCN
(vapor phase plus
particulate phase)
Flue-cured: native total volatile base sources
Control
flue-cured
0.07
0.37
13
168
246
Grade A
0.08
0.40
10
175
213
Grade B
0.06
0.44
14
189
213
Grade C
0.14
0.49
11
168
233
Grade D
0.13
0.58
14
199
219
Grade E
0.04
0.64
14
150
274
Flue-cured: added total volatile base sources
Control
flue-cured
0.07
0.37
13
168
246
Urea
0.07
0.49
15
166
256
Guanidine carbonate
0.08
0.57
17
204
328
(NH4)~0s
0.08
1.04
14
148
179
(NH4)2HP04
0.08
1.55
19
176
343
NH4CI
0.09
1.99
25
217
288
(NH4)~04
0.08
2.00
25
202
589
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61
the additives and to pH effects. Generally, additives
resulting in a basic environment would depress the
HCN level, whereas those lowering the pH would
elevate it.
REFERENCES
1. Baker, R. R., and K. D. Kilbum: The distribution
of gases within the combustion coal of a cigarette;
Beirr. Tabakforsch. 7 (1973) 79-87.
2. Baulch, D. L., D. D. Drysdale and D. G. Home:
Evaluated kinetic data for high temperature reactions, Vol. 2, Homogeneous gas phase reactions of
the H 2-Nr02 system; Chemical Rubber Company
Press, Cleveland, Ohio, pp. 285-300.
3. Brunnemann, K. D., and D. Hoffmann: Chemical
studies on tobacco smoke, XXV. On the pH of
tobacco smoke; Food Cosmet. To~col. 12 (1974)
115-119.
4. Brunnemann, K. D., L. Yu and D. Hoffmann:
Chemical studies on tobacco smoke, XLIX. Gas
chromatographic determination of hydrogen cyanide
and cyanogen in tobacco smoke; J. Anal. Toxicol.
1 (1977) 38-42.
5. Collins, P. F., N. M. Sarji and J. F. Williams: An
automated method for determination of hydrogen
cyanide in cigarette smoke; Tob. Sci. 14 (1970)
12-15.
6. Cooper, P. J., and R. B. Hege: The oxidation of
NO to N0 2 in cigarene smoke; Paper presented at
the· 32nd Tobacco Chemists' Research Conference,
Montreal, Canada, 1978.
7. Hardy, D. R., and M. E. Hobbs: The use of 15N
and of 15N and 16() in added nitrates for the study
of some generated constituents of normal cigarette
smoke; Proceedings of the 173rd American Chemical Society Meeting (Agricultural and Food Chemistry Division), Symposium on Recent advances in
the chemical composition of tobacco and tobacco
smoke, New Orleans, La., 1977, pp. '489-510.
62
8. Johnson, W. R., R. W. Hale, S. C. Clough and
P. H. Chen: Chemistry of the conversion of nitrate
nitrogen to smoke products; Nature 243 (1973)
223-225.
9. Johnson, W. R., R. W. Hale, J. W. Nedlock,
H. J. Grubbs and D. H. Powell: The distribution
of products between mainstream and sidestream
smoke; Tob. Sci. 17 (1973) 141-144.
to. Klimisch, H. J., and E. Kirchheim: Zur quantitativen Bestimmung von Stickoxyden in Zigarettenrauch mit Hilfe der Chemilumineszenzmethode;
Z. Lebensm. Unters. Forsch. 163 (1977) 48-52.
11. Lanzillotti, H. V., and A. R. Wayte: One-dimensional gas concentration proHles within a burning
cigarette during a puff; Beitr. _Tabakforsch. 8 (1975)
219-224.
12. Newsome, J. R., and C. H. Keith: Variation of the
gas phase composition within a burning cigarette;
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Authors' address:
Lorillard Research Center,
Greensboro, North Carolina, 27420,
U.S.A.
Unauthenticated
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