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Smoke chemistry analysis

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Smoke chemistry analysis is a well established and useful starting point for characterising a new product. Smoking machines - set to replicate different smoking regimes – provide reliable and reproducible methodology to collect and subsequently measure various smoke toxicants, even though machines do not mimic human smoking.

It is uncertain which smoke toxicants are the most important in the various diseases associated with smoking but we are carrying out research to try and prioritise these toxicants. The aim is to focus on the most biologically relevant constituents of smoke and reduce the amount found in cigarette smoke, which will give us the best chance of succeeding in our technology development.

Smoke chemistry

More than 5,000 smoke constituents have been identified in cigarette smoke and around 150 of these have been identified as smoke toxicants with biological activity.

Over the last 20 years researchers and public health organisations have drawn up toxicant lists comprising sub-sets of these constituents - the most widely cited being the ‘Hoffmann Analytes’ list of 44 constituents [1].

The Hoffmann analytes and their ISO mainstream yields for a 2R4F reference cigarette from University of Kentucky can be found below [2].

Group Analytes Molecular Weight Average Yields
Aromatic Amines 1-Aminonaphthalene (ng/cig) 143 15.1
2-Aminonaphthalene (ng/cig) 143 10.3
3-Aminobiphenyl (ng/cig) 169 3
4-Aminobiphenyl (ng/cig) 169 1.7
Carbonyls Methyl ethyl ketone (μg/cig) 72 62.72
Acetaldehyde (μg/cig) 44 560.48
Acetone (μg/cig) 58 264.74
Acrolein (μg/cig) 56 58.77
Butyraldehyde (μg/cig) 72 29.58
Crotonaldehyde (μg/cig) 70 16.18
Formaldehyde (μg/cig) 30 21.61
Propionaldehyde (μg/cig) 58 43.92
Phenols Catechol (μg/cig) 110 37.9
Hydroquinone (μg/cig) 110 32.4
m+p-Cresol (μg/cig) 108 5.84
o-Cresol (μg/cig) 108 1.89
Phenol (μg/cig) 94 7.32
Resorcinol (μg/cig) 110 0.91
Polycyclic Aromatic Hydrocarbon (PAH) Benzo[a]pyrene (ng/cig) 252 7
Inorganics Ammonia (μg/cig) 17 11.02
Hydrogen Cyanide (μg/cig) 27 109.2
Nitric Oxide (μg/cig) 30 223.41
Carbon Monoxide (mg/cig) 28 11.96
Organics Acrylonitrile (μg/cig) 53 8.28
Volatile Hydrocarbons 1,3-Butadiene (μg/cig) 54 29.94
Benzene (μg/cig) 78 43.39
Isoprene (μg/cig) 68 297.68
Toluene (μg/cig) 92 64.91
Styrene (μg/cig) 104 5.11
Nitrogen Heterocyclics Pyridine (μg/cig) 79 7.02
Quinoline (μg/cig) 129 0.23
Nicotine (mg/cig) 165 0.75
Metals & Metalloids Arsenic (ng/cig) 75 10.4
Cadmium (ng/cig) 112 47.8
Chromium (ng/cig) 52 73
Lead (ng/cig) 207 33
Mercury (ng/cig) 201 3.82
Nickel (ng/cig) 59 5.12
Selenium (ng/cig) 79 34.9
Tobacco Specific Nitrosamines (TSNAs) NAB (ng/cig) 191 16.3
NAT (ng/cig) 189 119
NNK (ng/cig) 207 115.6
NNN (ng/cig) 177 133.1
'Tar' Nicotine-free-dry-particulate-matter (mg/cig) - 8.91

In recent years the ISO machine smoking regime has been criticised for underestimating the actual exposure of individuals to smoke from cigarettes, leading some researchers to use more intense smoking regimes in exposure studies. 


No machine smoking regime can possibly predict exposure in all smokers so at British American Tobacco we typically use several regimes to measure the toxicant yields of a reduced toxicant prototype, including the Health Canada Intense regime.

Understanding the role of smoking regime on smoke chemistry and yields

We have studied the influence of different smoking parameters on smoke and constituent yields using methods originally developed to analyse our conventional products.  

Below is a table of different machine smoking regimes [3].

  ISO Method Massachusetts Canadian 'Intense'
       
Puff volume (cm3) 35 45 55
Puff frequency (s) 60 30 30
Puff duration (s) 2 2 2
Vent blocking (%) 0 50 100

Using these methods we have examined the effects of cigarette components and design parameters on yields under different smoking regimes, allowing us to predict toxicant yields from different cigarette design parameters [4]

A recent review identified the role of alternative smoking regimes in influencing overall smoke and individual toxicant yields, using study data from 1997 to 2006 [3]

Briefly, mainstream smoke yields as measured by smoking machines increase as larger puff volumes, more frequent puffs are taken, or filter vent-blocking is applied to highly ventilated cigarettes.  This is largely the result of more tobacco being consumed during a puff to form mainstream smoke.  Many possible changes may occur within the burning cigarette as the cigarettes are smoked with different smoking regimes.  However, the extent of the change to the mainstream smoke composition, as contributed from various smoke formation mechanisms (combustion, pyrolysis, pyrosynthesis and direct transfer) has not been systematically studied.

Measuring toxicants

The availability of robust and reliable analytical methods are the key to measuring - and in turn reducing - smoke toxicant yields from reduced toxicant prototypes.

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Accurately measuring and removing smoke toxicants has posed significant technical challenges, partly due to;

  • the low yields of many toxicants
  • their reactive nature
  • the complexity of the tobacco smoke matrix. 

The difficulties of reliably measuring smoke toxicant yields were reported in a cross-industry, joint-sponsored study of the Hoffmann analyte yields from cigarettes on sale in the UK [5].  This study illustrated the challenges in developing analytical methods for smoke toxicants and the presence of significant inter-laboratory differences in yields. 

Our analytical scientists continue to refine methods to measure toxicant yields by reviewing and modifying our analytical methods.  We have recently detailed our approaches to the determination of pyridines [6] and aromatic amines [7] as well as general issues around chromatographic sample preparation [8]. We have actively participated in cross-laboratory method assessment activities to ensure that our methods are as accurate and reliable as possible [2, 5].

Examining the potential role of other smoke constituents in smoking and health

There have been suggestions that free radicals in cigarette smoke may play a role in the development of smoking related diseases.  Although evidence for this is currently limited, we seek to understand the relevance of these agents to disease processes.  

As a first step we developed reliable analytical techniques for quantifying free radicals in smoke [9-15], indicating that there are 1014 – 1015 spins per cigarette in the gas phase of smoke. In short, we developed a spin-trapping methodology, in which it is possible to measure shortlived free radicals in both the gaseous and particulate phase of mainstream cigarette smoke. By spin trapping the gas phase free radicals, the oxidation products derived from the corresponding spin trap can be clearly seen by EPR ( Electron Paramagnetic Resonance) spectroscopy.

Since then we have begun to identify the free radicals formed in smoke and different types of spin traps have been used to trap different transient gas-phase radical species [10-16].  We have also observed carbon and oxygen-centred gas phase free radical species and quinonic radicals in the particulate phase of cigarette smoke.  However, it remains a very challenging task to distinguish the toxicological potential of free radicals generated in smoke from those of the other known toxicants. 

Improving measurement techniques

Minimising the influence of sample ageing and artefact formation on toxicant yields is a major research challenge in this area. 

A second challenge is to develop methods for analysing toxicants on a time resolved basis and on time-scales relevant to their formation.  This is essential if we are to relate toxicant yields to the mechanisms involved in their formation.

We are working with other research centres to develop new analytical techniques which offer a closer insight into the genesis of tobacco smoke toxicants [16,17].  

Below is a single photon ionisation (SPI) time profile of propyne (40m/z), acetone (58m/z) and isoprene (68m/z) recorded during the smoking of a Kentucky 2R4F reference cigarette [17].

A single photon ionisation (SPI) time profile of propyne (40m/z), acetone (58m/z) and isoprene (68m/z) recorded during the smoking of a Kentucky reference cigarette


  1. Hoffmann, D., Hecht, S. S. (1990). Chapter 3: Advances in tobacco carcinogenesis. In: Cooper, D. S., Grover, P. eds. Chemical carcinogenesis and mutagenesis. London: Springer-Verlag.
  2. Chen, P. X., Moldoveanu, S. C. (2003). Mainstream smoke chemical analyses for 2R4F Kentucky reference cigarette. Beiträge zur Tabakforschung International. 20 (7): 448-458.
  3. Dixon, M., Borgerding, M. F. (2006). Recent advances in the application and understanding of alternative smoking regimes. Recent Advances in Tobacco Science. 32: 3-84. 
  4. Sheppard, J., Warren, N., Case, P. D. (2005). The effect of cigarette design variables on assays of interest to the tobacco industry: 2) Prediction of Hoffmann analytes using two different modelling methods. Oral presentation made at the CORESTA Joint Meeting of the Smoke Science and Product Technology Study Groups, Stratford-upon-Avon, UK, September 4-8, 2005.  PDF: PDF: The effect of cigarette - prediction… - PDF: The effect of cigarette - prediction… (260 kb) Opens new window
  5. Gregg, E., Hill, C., Hollywood, M., Kearney, M., McLaughlin, D., McAdam, K., Williams, M., Purkis, S. (2004). The UK smoke constituents testing study. Summary of results and comparison with other studies. Beiträge zur Tabakforschung International. 21 (2): 117-138.
  6. Kulshreshtha, N. P., Moldoveanu, S. C. (2003). Analysis of pyridines in mainstream cigarette smoke. Journal of Chromatography A. 985 (1): 303-312.
  7. Smith, C. J., Dooly, S., Moldoveanu, S. C. (2003). New technique using solid-phase extraction for the analysis of aromatic amines in mainstream cigarette smoke. Journal of Chromatography A. 991 (1): 99-107.
  8. Moldoveanu, S. C. (2004). Solutions and challenges in sample preparation for chromatography. Journal of Chromatographic Science. 42 (1): 1-14.
  9. Baum, S. L., Anderson, I. G. M., Baker, R. R., Murphy, D. M., Rowlands, C. C. (2003). Electron spin resonance and spin trap investigation of free radicals in cigarette smoke: Development of a quantification procedure. Analytica Chimica Acta. 481 (1): 1-13. Abstract: Electron spin resonance and  Opens new window
  10. Ghosh, M., Ionita, P. (2007). Investigation of free radicals in cigarette mainstream smoke. Paper presented at the 3rd European Combustion Meeting ECM, Crete, Greece, April 11-13, 2007.  PDF: PDF: Investigation of free radicals in... - PDF: Investigation of free radicals in... (530 kb) Opens new window
  11. Ghosh, M., Ionita, P., McAughey, J., Cunningham, F. (2008). Electron Paramagnetic Resonance of the Free Radicals in  the Gas- and Particulate Phases of Cigarette Smoke using Spin-Trapping. Accepted for publication in: Journal of Organic Chemistry-ARKIVOC.
  12. Ghosh, M., Cunningham, F., McGrath, C., Baker, R. R., McAughey, J. (2006). Development of a quantification method for free radicals in cigarette smoke by electron spin resonance. Poster presented at the 39th International Conference on Advanced Techniques & Applications of EPR, organized by the Electron Spin Resonance Group of the Royal Society of Chemistry, Edinburgh, Scotland, April 2-5, 2006.  PDF: PDF: Development of a quantification… - PDF: Development of a quantification… (240 kb) Opens new window
  13. Ghosh, M., Cunningham, F., Baker, R. R., McAughey, J. (2006). Development of a quantification method for free radicals in cigarette smoke by electron spin resonance. Poster presented at the EUCHEM Conference on Organic Free Radicals, Scandanvian Collaboration, Bergen, Norway, July 9-13, 2006.  PDF: PDF: Development of a quantification… - PDF: Development of a quantification method… (361 kb) Opens new window
  14. Ghosh, M., Ionita, P. (2007). Investigation of free radicals in cigarette mainstream smoke. Paper presented at the 3rd Biennial Meeting of the Society for Free Radical Research - Asia (SFRR Asia) & 6th Annual Meeting of the Society for Free Radical Research – India (SFRR India), Lonavala (near Mumbai), January 8-11, 2007.  PDF: PDF: Investigation of free radicals in cigarette… - PDF: Investigation of free radicals in cigarette… (223 kb) Opens new window
  15. Ghosh, M., Ionita, P., McAughey, J., Cunningham, F. (2007). An investigation of oxygen centred free radicals in cigarette smoke by electron spin resonance. Poster presented at the 40th Annual International Meeting of the Electron Spin Resonance Group of the Royal Society of Chemistry, New College, Oxford, March 25-29, 2007.  PDF: PDF: An investigation of oxygen… - PDF: An investigation of oxygen… (824 kb) Opens new window
  16. Adam, T., Streibel, T., Mitschke, S., Muhlberger, F., Baker, R. R., Zimmermann, R. (2005). Application of time-of-flight mass spectrometry with laser-based photoionization methods for analytical pyrolysis of PVC and tobacco. Journal of Analytical and Applied Pyrolysis. 74 (1-2): 454-464. Abstract: Application of time-of-flight... Opens new window
  17. Mitschke, S., Adam, T., Streibel, T., Baker, R. R., Zimmermann, R. (2005). Application of time-of-flight mass spectrometry with laser-based photoionization methods for time-resolved on-line analysis of mainstream cigarette smoke. Analytical Chemistry. 77 (8): 2288-2296. Abstract: Application of time-of-flight mass...  Opens new window
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