Volumen 8 (1975): Edición 3 (August 1975)

Volatile N-nitrosamines were determined in the vapour phase of tobacco smoke after accumulation of Iarge vapour samples on to a cooled capillary GLC column. Detection was effected by computerized mass spectrometry and by a nitrogen-specific detector. Five different tobacco products were studied with mass spectrometry for the presence of eight individuaI nitrosamines. The result was negative thirty-nine times and positive only once. Initially, the detection Iimit for the individual nitrosamines was 2 ng per 20-55 mI vapour injection; during this study the effective detection limit was Iowered for some of the compounds by a further twofold to fivefold increase of the vapour volume analysed. The one nitroso compound identified positively and unambiguously was N-nitrosopiperidine in the smoke from the American blend cigarettes. It amounted to about 5.6 ng in the vapour phase of the smoke of one cigarette. The partition of nitrosamines between vapour phase and particulate phase is not known, but amounts of more than 1 µg of dimethylnitrosamine or nitrosopiperidine in the whole smoke of one cigarette as found by some authors, seem improbably high. It is shown in this paper that exclusive use of the alkali flame ionization detector for nitrosamine determinations would have led to false-positive results, especially for dimethylnitrosamine.

The draw resistance of a cigarette increases by about 50-60 % when the cigarette is lit, and the total draw resistance of the burning cigarette varies in a distinct manner as it is smoked. This effect is not normally due to an inherent increase in the impedance of the coal, because the effect disappears when the cigarette is extinguished. Rather, the effect is due to the heating of the gases flowing through the coal and down the tobacco rod, in particular (a) the increase in gas viscosity with temperature, (b) the increase in volumetric gas flow due to thermal expansion, and (c) the increase in the impedance of the unburnt tobacco rod, due to the deposition of smoke condensate on the rod. A hot-gas model, using the above contributing factors together with the known gas-phase temperature distribution inside the burning cigarette, can predict quantitatively (within the limits of experimental error) the observed variations of the draw resistance of a burning cigarette.

Cigarette smoke condensate (CSC) was fractionated for bioassay to determine possible tumorigenic activity on mouse skin. Two fractions which previously had shown activity were further separated. A weak-acid fraction (F 8) was separated into three subfractions. A polynuclear aromatic hydrocarboncontaining fraction (F 20) was divided into two fractions by gel permeation chromatography. The polynuclear aromatic hydrocarbons, the suspected active materials in F 20, were successfully concentrated into a fraction (F 55) representing only 0.05 % of CSC. These materials are currently undergoing bioassay.

Smoke from gamma irradiated 1R1 Reference cigarettes was compared to smoke from the non-irradiated cigarettes. Total particulate matter, nicotine, and tar levels decreased with increasing radiation dose. Nicotine was determined by gas chromatography, using 7-methyl- quinoline as an internal standard. Yields of solvent partition fractions of the smoke condensate and of chromatographic fractions of the condensate neutrals did not indicate significant changes in smoke composition resulting from gamma irradiation of the precursor cigarette tobacco. The composition of refined polycyclic aromatic hydrocarbon (PAH) fractions of smoke from irradiated cigarettes appeared to be identical to that of standard cigarettes. The expected decrease in PAH did not occur. It was concluded that gamma irradiation of cigarettes had no major effects on smoke composition.

A procedure has been developed to collect, transfer, and analyse volatile organic pyrolysis products of tobacco leaf compounds. The volatiles were collected in a series of three traps on adsorbents that also served as substrates for transfer and for introduction of the volatiles into a gas chromatograph. Analytical procedures are described for three gas chromatographic columns packed, respectively, with the three different adsorbents used in the traps. With this system, volatile pyrolyzates were collected and analysed without the use of cryogenic traps, vacuum manifolds, or gas-sampling valves. The applicability of the procedures is demonstrated for the pyrolysis volatiles of stearic acid, a tobacco constituent

The purpose of this investigation was to attain a better understanding of the selective removal of certain compounds from cigarette smoke by filters. A gas chromatographic method for the determination of selected semivolatile smoke compounds was developed. The method, which utilizes a 160 m glass capillary column, was used to determine the efficiency of filters for the removal of these selected semivolatile compounds. A correlation was found between the selective filtration of these compounds from cigarette smoke and their distribution coefficients [K_d = (g compound/g filter)/ (g compound/cm³ air)] between air and various filter materials. In addition, a correlation was found between the physicaI and chemical nature of certain smoke compounds and their selective filtration. Previous work indicated that if a compound is to be selectively removed from tobacco smoke by a filter, [1] a significant portion of that compound should be in the vapour state as it passes through the filter and [2] the compound should have an affinity for the filter material. The relative rate of vapourization (R_v) was used as a measure of 1., and the totaI solubility parameter (d) was taken as a measure of 2. Values for the vapourization rate were calculated from the product, vapour pressure (P), molecular weight (M), and diffusion coefficient (D), (R_v = kPMD^1/2). The correlation of R_v and δ with the selectivity (S_x) of cellulose acetate filters for smoke compounds is described by

S_x = b₀ + b₁δ + b₂δ (1n R_v),

where b₀, b₁, and b₂ are constants. This equation may be used to predict the selective filtration of semivolatile compounds from cigarette smoke.

The semivolatile portion of cigarette smoke contains acidic, basic, and neutral compounds that are important to the flavour and in some cases the physiological effects of smoke. A rapid method that could be used routinely for the gas chromatographic analysis of this portion of smoke was developed. A 160 mm glass capillary column was used to resolve approximately 150 semivolatile smoke components. Gas chromatography - mass spectrometry was used to identify about 35 of these components. Twenty known semivolatile compounds with different functional groups and boiling points were used to determine the effects of various filters on their removal from smoke. Standard cellulose acetate filters, cellulose acetate filters with glycerin, cellulose acetate filters with PEG 600, and cellulose acetate filters with activated carbon were evaluated. The cellulose acetate filters with glycerin and PEG 600 were more selective for the removal of aromatic hydrocarbons than were the standard cellulose acetate filters. The cellulose acetate filters with activated carbon were more selective for the removaI of the low-boiling semivolatile compounds than were the other filters tested.

An eight-channel smoking attachment for the collection of the vapour phase from cigarettes has been developed. The utilisation of the device for the simultaneous puff by puff measurement of carbon monoxide, carbon dioxide and nitric oxide is described. The attachment has been constructed for use with the CSM 300 smoking machine but could readily be adapted for use with other smoking machines.

A brief survey is given of the physical and chemical characteristics of celluIose ethers, which is gaining importance in industry. On the strength of patent literature, reference is made to the technological uses of cellulose ethers in the tobacco industry. A microscopical method of establishing the presence of cellulose ethers in reconstituted leaf and in new smoking products is described and reference is made to differences between methyI celluloses and carboxymethyl celluloses as they appear during the investigation. Other qualitative reactions and possibilities of quantitative determination are also summarised.