- Dettagli della rivista
- Pubblicato per la prima volta
- 01 Jan 1992
- Periodo di pubblicazione
- 4 volte all'anno
- Accesso libero
Determination of Environmental Tobacco Smoke from a Second-Generation Electrically Heated Cigarette Smoking System and Conventional Cigarettes
Pagine: 1 - 7
This substudy of a randomized, controlled, forced switching, open-label, parallel-group clinical study in a total of 100 healthy adult male and female smokers compared environmental tobacco smoke (ETS) produced from smoking a second generation electrically heated cigarette smoking system (EHCSS), two conventional cigarettes, and no-smoking. Concentrations of air constituents including respirable suspended particulate matter (RSP), carbon monoxide (CO), and total volatile organic compounds (TVOCs) and ETS markers including solanesol-related particulate matter (Sol-PM), ultraviolet absorbing particulate matter (UVPM), fluorescing particulate matter (FPM), nicotine and 3-ethenylpyridine (3-EP) were measured in a ventilated, furnished conference room over a period of 2 hours on separate occasions. Except for TVOCs, concentrations of air constituents and ETS markers were reduced by 40% to more than 90% when adult smokers were smoking the EHCSS as compared to smoking conventional cigarettes. CO and most ETS marker concentrations were in the same range as no-smoking.
- Accesso libero
A Modelling Approach to Develop Machine Smoking Protocols Reflecting Human Puffing Behaviour for Conventional Cigarettes
Pagine: 8 - 18
Our objective was to develop machine-smoking protocols (i.e. puff volume, puff duration and puff frequency) reflecting the distribution of human smoking behaviour as a complement to the International Standard (ISO) protocol. For this purpose, a modelling approach based on smoking topography and excretion data of urinary nicotine metabolites from clinical studies in the UK and Japan was used.
Three smoking protocols (LOW, MEDIUM and HIGH) were based on the 10th percentile, the mean and the 90th percentile of the puff volumes obtained from topography data. The corresponding puff durations were estimated by linear regression analysis of the puff duration/puff volume relationship. Finally, puff frequency was estimated using a predictive model assuming that the nicotine yield is a linear function (i.e. proportional) to the amount of air actually drawn through the burning part of the cigarette. This approach was termed ‘
Although smoking virtually identical cigarettes, smoking protocols based on topography and excretion data of urinary nicotine metabolites from the UK clinical study were different than those based on data from the study performed in Japan. This may be explained by different smoking behaviour between these two populations of smokers.
- Accesso libero
Pagine: 19 - 31
This report evaluates the formation of nitrosonornicotine (NNN) and of 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) from nicotine, and of NNN from nornicotine in the mainstream smoke of a burning cigarette. The cigarettes analyzed in the study were Kentucky reference cigarettes 1R4F and 2R4F, and five other cigarettes, three of them having tobaccos with low levels of tobacco specific nitrosamines (TSNAs). All cigarettes had ‘tar’ levels around 10 mg [where ‘tar’ is defined as the weight of total wet particulate matter (TPM) minus the weight of nicotine and water]. Cigarettes were smoked according to the U.S. Federal Trade Commission (FTC) puffing regimen, using a 35 mL puff volume, 2 sec puff duration and 60 sec puff intervals. Three separate experiments were performed in this study to evaluate the proportion of TSNAs transferred from preexistent tobacco TSNAs and the proportion formed during smoking (pyrosynthesized). In one experiment, the results were obtained by GC/MS analysis of 13C3-TSNAs formed in smoke when 13C3-nicotine was intentionally added to cigarettes. Another experiment used GC analysis with chemiluminescence detection of TSNAs from smoke before and after an excess of nornicotine was intentionally added to cigarettes, and another experiment consisted of LC/MS/MS analysis of 2H4-TSNAs formed in the smoke when 2H4-nicotine and when 2H4-nornicotine were intentionally added to cigarettes. The use of different analytical methods for the study of TSNA formation conveyed an additional level of confidence regarding the reliability of the results obtained. It was found that NNK was generated during smoking from nicotine with 3 × 10-5% to 8 × 10-5% conversion (0.3 ppm to 0.8 ppm conversion of the nicotine) while the result for NNN generation was not conclusive. One experiment demonstrated the formation of NNN from nicotine between 4 × 10-5% and 1.5 × 10-4% (0.4 ppm to 1.5 ppm reported to nicotine), but another experiment did not provide proof of NNN formation, with a limit of quantitation LOQ for NNN corresponding to 5 × 10-5% (or 0.5 ppm). Nornicotine was proven to generate NNN, and the results for the 2R4F cigarette showed 3.3 × 10-3% yield (33 ppm reported to nornicotine) in one experiment and 4.6 × 10-3% (46 ppm reported to nornicotine) in a different experiment, the agreement being very good. Using the results from this study, it was concluded that pyrosynthesis may account for about 5% to 10% of the NNK in mainstream smoke for a filter cigarette with the FTC ‘tar’ level around 10 mg. Pyrosynthesis may account for higher proportions of smoke TSNAs when the cigarette tobacco is low in TSNAs, since the mainstream smoke TSNAs yield from direct transfer from tobacco is small in this case. The contribution of pyrosynthesis may account for 5% to 25% of NNN in mainstream cigarette smoke, or potentially an even higher proportion when the tobacco blend is both low in TSNAs and high in nornicotine. Anabasine is typically present at low levels in tobacco and therefore the formation of nitrosoanabasine(NAB) is of less interest. Anatabine is present in different tobaccos in a range similar to that of nornicotine and being a secondary amine has the potential to act similarly to nornicotine. However, the pyrosynthesis of nitrosoanatabine (NAT) from anatabine was not evaluated in the present study. The study indicated that complete elimination of TSNAs from tobacco is unlikely to completely eliminate the TSNAs from cigarette smoke, and that high nornicotine tobaccos should be avoided in order to minimize the levels of NNN in cigarette smoke.
- Accesso libero
Isolation, Fractionation, and Identification of Sucrose Esters from Various Oriental Tobaccos Employing Supercritical Fluids
Pagine: 32 - 45
Isolation, fractionation, and identification of sucrose esters from aged oriental tobacco employing supercritical fluids have been completed. Underivatized sucrose ester-rich extracts were obtained using supercritical CO2 at densities greater than 0.73 g/mL. Lower density CO2 provided extracts with notable amounts of tobacco derived material; yet, no detectable sucrose ester content. Preparative supercritical fluid chromatography (SFC) provided for an additional purification of the sucrose ester-enriched fraction after column optimization. Structural assignments of the SFC fractions were facilitated using gas chromatography/mass spectrometry (GC/MS) accompanied by N, O-bis(trimethylsilyl)trifluoroacetamide-dimethylformamide (BSTFA-DMF) derivatization of the free hydroxyl groups and high performance-liquid chromatography/mass spectrometry (HPLC/MS). From a relative quantitative perspective regardless of tobacco type, sucrose esters having an acetyl group on C6 of the glucose function (Group III) were in higher concentration compared to both the concentration observed for sucrose ester of Group I (acetyl group on C3 of fructose) and sucrose ester of Group II (no acetyl group on either glucose or fructose). Saturated fatty acid constituents were found to range from a maximum total of 18 carbons to a minimum total of 13 carbons. Unsaturated and isomeric fatty acid homologues were detected within the Group II sucrose ester.
- Accesso libero
Pagine: 46 - 62
The burning cycles of a lit-end cigarette were numerically simulated using a 3-D model that includes both the cigarette and its surrounding ambient air and the effects of buoyancy forces. The solid and gas phases were treated separately in a thermally non-equilibrium environment. The tobacco pyrolysis and char oxidation were modeled using multi-precursor models. The changes in tobacco column porosity and its subsequent effects on permeability and gas diffusivity were included. The mass, momentum, energy, and species transport equations were solved in a discretized computational domain using a commercially available computational fluid dynamics (CFD) code. The model was applied to puff a cigarette under different puffing intensities and the effects of puff volume, puff profile, and puff duration were studied. The results show that the model is capable of reproducing the major features of a burning cigarette during both smoldering and puffing. For the puffing and puff-by-puff cases, the solid and gas temperatures as well as those mainstream smoke constituents predicted by the model are in a good agreement with experimental results. A parametric study shows the significant effect of puff volume, puff profile, ventilation rate, and puff counts on solid and gas phase temperatures as well as gaseous species concentrations and mainstream smoke delivery. The buoyancy forces have shown to be very important in both smoldering and puffing.
- Accesso libero
Pagine: 63 - 65