- Détails du magazine
- Format
- Magazine
- eISSN
- 2719-9509
- Première publication
- 01 Jan 1992
- Période de publication
- 4 fois par an
- Langues
- Anglais
Chercher
- Accès libre
Chemical Studies on Tobacco Smoke: LI: Studies on Non-Volatile Nitrosamines in Tobacco
Pages: 1 - 6
Résumé
Various factors which might contribute to the presence of or reflect on the formation of N'-nitrosonornicotine (NNN) or related nitrosamines in tobacco were studied. Using high-performance liquid chromatography (HPLC), the E- and Z-isomers of NNN were clearly separated and the rates of interconversion were determined. The E/Z ratio in tobacco approximated that observed in solution at similar pH and temperature. The influence of curing and stalk position on NNN levels in tobacco was determined. NNN was not detected in green tobacco but was detected in air-cured leaves from the same crop. No significant correlation was observed among stalk position and NNN levels in one variety of bright tobacco. Since NNN may derive from nicotine, two new nitrosamines, a nitrosamino ketone and a nitrosamino aldehyde, which could theoretically arise from nicotine, were synthesized. Analysis of tobacco for these components is currently in progress
- Accès libre
Differential Thermal Analysis of Tobacco as a Function of Heating Rate
Pages: 7 - 12
Résumé
The differential thermal analysis of reconstituted tobacco sheet heated at rates of 0.1°C/s to 500°C/s in an inert atmosphere is reported. As the heating rate is increased, the characteristic temperature of each global process observed is increased. Using a non-isothermal first-order kinetic equation, the activation energies and frequency factors are obtained for these bulk decomposition processes
- Accès libre
Rapid Spectrophotometric Analysis of the Chemical Composition of Tobacco: Part 1: Total Reducing Sugars
Pages: 13 - 18
Résumé
The log10 (1/R) spectra, from 1.4 to 2.4 µm, of 152 samples of comminuted samples of tobacco were recorded on a computerized spectrophotometer. The parameter d2 (log (1/R)) / d λ2 was calculated for each spectrum and correlated with chemical analyses of total reducing sugars using the method proposed by Harvey et al. (12). A nine-term multiple-linear regression relating the above parameter at seven different wavelengths to total reducing sugar gave a correlation coefficient of 0.990 and a standard error of ± 1.15 percent. Instrument noise was found to contribute over 50 percent of the total variance.
- Accès libre
Use of Ion-Selective Electrodes in Tobacco and Tobacco Smoke Analyses: A Review
Pages: 19 - 22
Résumé
Ion-selective electrodes have been used for the rapid determination of many components in tobacco and tobacco smoke. The determinations of the following tobacco smoke components with ion-selective electrodes are reviewed: hydrogen sulfide with a sulfide electrode, hydrogen cyanide with a cyanide electrode, nitrogen oxides with a nitrate electrode, and ammonia with an ammonia electrode. The determination of nitrate and ammonia in tobacco is also described. Some possible applications of ion-selective electrodes are discussed, based on the electrode sensitivity and selectivity and the level of certain components in tobacco or tobacco smoke
- Accès libre
Correlation of Polynuclear Aromatic Hydrocarbon Formation Between Pyrolysis and Smoking
Pages: 23 - 37
Résumé
Tobacco, its petroleum ether (PE) extract, and the residual extracted tobacco (marc) were pyrolyzed at 650-750°C, 650-850°C, and 700°C, respectively. Analyses of the polynuclear aromatic hydrocarbons (PAH) produced showed that the pyrolysis of the tobacco and the PE extract at 700°C produced PAH profiles comparable to those found in cigarette smoke condensate (CSC). The data indicated that most of the alkyl PAH and the major PAH in cigarette smoke are derived from the PE extractables of tobacco. The constituents of the marc were the major precursors for phenols, oxygenated PAH, and Iow molecular weight acids; and those of PE extract were the major producers of high molecular weight acids.
- Accès libre
Determination of Carbon Monoxide in Cigarette Smoke Using an Electrochemical Transducer
Pages: 38 - 44
Résumé
A system for the in-line measurement of puff-by-puff levels of carbon monoxide on a Filtrona 300 smoking machine during routine smoking of cigarette for tar and nicotine yields has been developed. The technique involves the introduction of a transducer into the suction line behind the Cambridge filter. This transducer comprises an electrochemical cell bridged by a pair of solenoid valves which are under the control of the cotton gate smoking terminator. These valves are actuated, other than at the butt mark, by an additional inductive timing switch on the crankshaft. Results using this technique compare well with results from existing off-Iine techniques such as gas-solid chromatography
- Accès libre
Thermal Decomposition of Tobaccos: VII: Influence of Atmosphere on the Formation of Gas Phase Constituents
Pages: 45 - 52
Résumé
Formation profiles have been obtained for methane, ethane, ethene, propane, propene, butanes, butenes, isoprene, formaldehyde, acetaldehyde, acetone, 2-butanone, benzene, and toluene from the thermal decomposition of tobacco in the presence of helium and air. These data show that in helium the temperatures for optimum formation of gas phase constituents were: hydrocarbons, 450°C; aldehydes, 300°C; ketones, 450°C; isoprene, 380° and 475°C; and aromatic hydrocarbons, 450°C. Air enhances the formation of these gas phase constituents at 280°C and in most cases at 420°C, the latter temperature is an area of major weight loss of tobacco. Each formation maximum corresponds to a rate of weight loss maximum exhibited by derivative thermogravimetry. The results also show that it is possible to use effluent gas analysis to define the thermal behaviour of tobacco in terms of the formation of the gas phase constituents which provide a means to elicit the processes that occur during the thermal decomposition of tobacco.
- Accès libre
The Effect of Bruising on Starch Degradation in Virginia Tobacco Leaves
Pages: 53 - 57
Résumé
The effect of bruising Virginia-type tobacco leaves on starch degradation during yellowing has been investigated. Bruising suppressed starch degradation in greenhouse-grown leaves completely and by about half in field-grown leaves. The increase in sugar levels which normally occurs during yellowing was also suppressed by bruising; in the greenhouse-grown leaves this suppression was complete but in the field-grown leaves it was only partial. As the greenhouse-grown plants ripened, the rate of starch degradation in unbruised leaves held in yellowing conditions decreased substantially. Bruising also suppressed the chlorophyll degradation which normally occurs during yellowing. However, in this case bruising produced a greater degree of suppression in the field-grown than in the greenhouse-grown Ieaves. As the greenhouse-grown plants ripened, the rate of chlorophyll degradation in unbruised leaves held in yellowing conditions increased substantially, in marked contrast with the behaviour of starch. Nicotine levels increased in the greenhouse-grown leaves as they ripened, but the levels were not affected consistently by bruising
- Accès libre
The Fate of Fatty Compounds and Surfactants Used as Sucker Control Agents on Field Tobacco
Pages: 58 - 62
Résumé
The fate of fatty compounds and surfactants used for tobacco sucker inhibition was studied with 14C-labelled materials applied to field-grown Nicotiana tabacum L. cv. Maryland Catterton plants. Residual materials recovered from test tobacco showed the following: [ 1 ] When lauric acid was used, the residual material was maintained essentially in the acid fraction. [2] When lauryI alcohol was used, a considerable part (9.7-24.8 %) was converted to the acid fraction, indicating possible oxidation of alcohol in the field; smaller amounts (7.4 to 14.8 %) were found in the ester fraction. [3] When methyl laurate was used, most (54-77 %) of the residue was recovered in the acid fraction, a small part (12.6 to 22.7 %) was found in the alcohol fraction, and the rest (10.3-23.3 %) remained in the ester fraction. [4] When Tween surfactants were used, nearly all the residual materials had been hydrolyzed to free polyol and fatty acids