- Dettagli della rivista
- Pubblicato per la prima volta
- 01 Jan 1992
- Periodo di pubblicazione
- 4 volte all'anno
- Accesso libero
A Method for the Automatic Determination of the Nitrate Content of Tobacco / Eine Methode zur automatischen Nitratbestimmung im Tabak
Pagine: 161 - 166
The method for determining nitrate in the form of a perrhenate complex has been modified for the purpose of automatically determining nitrate contained in tobacco with the Technicon Autoanalyser. The modified method makes it possible to determine automatically nitrate contents of aqueous tobacco extracts ranging from 0.03 % to the maximum amounts usually occurring in tobacco. The procedure described is suitable for the analysis of thirty tobacco samples per hour. The results correspond with those furnished by other manual techniques. The analytical data obtained by application of this method of analysis differ from those resulting from the photometric method using 3,4-dimethylphenol (Maastricht) by, on an average, less than 0.01 % nitrate. The coefficient of variation of this method is, with measurements from a homogeneous extract as well as from various amount weights of one tobacco sample, 2.5 %.
- Accesso libero
Chemical Studies on Tobacco Smoke: IV. The Quantitative Determination of Free Nonvolatile Fatty Acids in Tobacco and Tobacco Smoke
Pagine: 167 - 175
An analytical method was developed for the determination of nonvolatile free fatty acids in tobacco and tobacco smoke. Quantitative values were secured by employing stearic acid-1-C14 as internal standard for saturated acids, and oleic acid-9,10-H3 for unsaturated acids. The method yields exact values for the six major acids within AA± 7 % and can be applied as a micro method with as little as 10 to 20 mg starting material. The major free fatty acids in tobacco were found to be in order of decreasing concentration, linolenic, palmitic, linoleic, stearic, oleic, myristic, and palmitoleic acids. Further identified were C12, C14, C15 and all saturated acids between C20 and C26. The concentrations of the acids in tobacco were found to vary between 0.6 % and 0.09 % in the six tested samples. Higher concentrations of these components were found in flue-cured and sun-cured tobaccos compared with air-cured tobacco. Coumarin was identified in the concentrated methyl esters of Turkish and bright tobaccos as well as of the blended cigarette tobacco. The analysis of cigarette smoke resulted qualitatively in a similar acid spectrum as found for tobacco. However, the concentration of the five major fatty acids was found to be at least four times higher in the particulate matter than in the original tobacco. Assuming that these fatty acids in the mainstream smoke derive from the acids originally present in tobacco, one finds a recovery rate of about 16-34 %. These findings are of interest not only to the tobacco chemist but may have even broader implications because of the possible role that nonvolatile fatty acids play in the tumour promoting activity of tobacco smoke condensate
- Accesso libero
Pyrogenesis of Aromatic Hydrocarbons Present in Cigarette Smoke l: Role of the Hexane Soluble Fraction of Tobacco
Pagine: 176 - 181
The hexane soluble fraction of flue-cured tobacco has been pyrolyzed to reevaluate the importance of its contribution to the formation of aromatic compounds, especially polynuclear aromatic hydrocarbons (PAH), present in cigarette smoke. The pyrolyses were performed at 860° AA± 5°C under nitrogen. In general, the studies indicate that the hexane-solubles contribute significantly more to the aromatic hydrocarbon levels of tobacco pyrolysate than would be predicted on the basis of percent of dry leaf weight alone. Estimates of benzo[a]pyrene levels in pyrolysates indicate that nearly two-thirds of the amount produced during tobacco pyrolysis may be attributed to the hexane soluble components of leaf.
- Accesso libero
The Quantitative Determination of Insecticides in Tobacco and Tobacco Smoke. 1st Report: The Determination of Organochlorine Insecticides / Methoden zur quantitativen Bestimmung von Insektiziden in Tabak und Tabakrauch. I. Mitteilung: Zur Bestimmung von Organo-Chlor-Insektiziden
Pagine: 182 - 188
A method is presented for the determination of insecticides belonging in the group of chlorinated hydrocarbons (organochlorine insecticides) in tobacco and tobacco smoke. The described analytical procedure allows the rapid measurement of insecticide concentrations down to the detection limit of 0.01 ppm. Tobacco or tobacco smoke condensate is extracted with aqueous acetonitrile. The filtered extract is diluted with water, and the insecticide residues are then extracted with petroleum ether. The concentrated petroleum ether extract is chromatographically purified by passage over a Florisil column and, subsequently, eluted with mixtures of diethyl ether and petroleum ether (6 and 15 % of diethyl ether, respectively). After vacuum sublimation the concentrated eluates are qualitatively and quantitatively analysed by gas chromatography using an electron capture detector and by thin-layer chromatography. On an average, 8 % of chlorinated hydrocarbon insecticides contained in tobacco are shown to be transferred into the mainstream smoke.
- Accesso libero
Pagine: 189 - 195
The behaviour of smoke condensate (obtained from tobacco of Virginia type by electrostatic precipitation) and large smoke particles suspended on fine platinum wire was studied in moist air. The equilibrium vapour pressure of water over the surface of smoke condensate at 15°C was found to be 76.5 % of the saturation pressure, indicating that the apparent concentration of water soluble particulate matter in the smoke condensate is 1.2 × 10-3 g-mole g-1. The rate of growth of smoke particles suspended on fine wire in moist air was much slower than the rate predicted by Maxwell's theory. Apparently this is not caused by a rise in the temperature of the particle due to the heat liberated in the condensation process, but by a low value for the accommodation coefficient of the particle surfaces (1.5 × 10-4). These results suggest that smoke particles of 0.4 AAµ in diameter, in transit through the respiratory system during smoking, grow by picking up water from the moist pulmonary air by a factor of only 1.7 in mass or 1.2 in diameter. It is concluded that this increase in size is not large enough to affect significantly the rate of deposition of smoke particles in the respiratory tracts.