- Dettagli della rivista
- Pubblicato per la prima volta
- 01 Jan 1992
- Periodo di pubblicazione
- 4 volte all'anno
- Accesso libero
Pagine: 157 - 166
The permeability of a tobacco rod in a cigarette increases as it converts into char and ash in the coal. The hot coal introduces a significant resistance to the air flow when air passes through. Through a series of experiments, the cigarette burn line and burn rate, the centerline temperature, and the pressure drop were measured for continuous puffing conditions. The gas viscosity was calculated from the temperature distribution inside the cigarette and applying Sutherland's law. Then, the experimental setup was mathematically modeled from a commercially available CFD (Computational Fluid Dynamics) code and, by matching the numerical and experimental results, the changes in coal and filter permeability during puffing were estimated. The numerical simulation successfully reproduced the results of experiments on the air flow through the coal, ventilation holes and paper wrapper.
- Accesso libero
Compensation for the Effects of Ambient Conditions on the Calibration of Multi-Capillary Pressure Drop Standards
Pagine: 167 - 174
Cigarette draw resistance and filter pressure drop (PD) are both major physical parameters for the tobacco industry. Therefore these parameters must be measured reliably. For these measurements, specific equipment calibrated with PD transfer standards is used. Each transfer standard must have a known and stable PD value, such standards usually being composed of several capillary tubes associated in parallel. However, PD values are modified by ambient conditions during calibration of such standards, i.e. by temperature and relative humidity (RH) of air, and atmospheric pressure. In order to reduce the influence of these ambient factors, a simplified model was developed for compensating the effects of ambient conditions on the calibration of multi-capillary PD standards.
- Accesso libero
Gas Chromatographic-Selected Ion Monitoring-Mass Spectrometric Determination of Cigarette Mainstream Smoke Components with Sensory Attributes
Pagine: 175 - 183
A new method has been developed that detects significant quantitative differences in the amounts of pyrazines, pyridines, furfurals, carboxylic acids, b-damascenone, sclareolide, and megastigmatrienones in the mainstream smoke of a series of five commercial cigarettes. This new quantitative method is based on the gas chromatographic-selected ion monitoring-mass spectrometric (GC-SIM-MS) determination of the selected smoke constituents. The accuracy and precision of the approach were well within acceptable parameters with the majority of cases relative standard deviation (RSD) values consistently around 5%. Sample preparation was simple requiring only the dissolution of the trapped particulate material in a known volume of methanol followed by injection of this clear dark colored solution into the gas chromatograph. This approach represents an advance in the technology in terms of higher sample throughput and less sample workup. Certain products demonstrated consistent trends in concentration of specific chemical classes. The mainstream smoke from a University of Kentucky reference cigarette, 2R4F, was included for reference purposes. These results are applicable in the overall evaluation of the components responsible for the taste associated with cigarette products.
- Accesso libero
The Influence of Cigarette Moisture to the Chemistry of Particulate Phase Smoke of a Common Commercial Cigarette
Pagine: 184 - 191
This study presents the results on the influence of cigarette moisture content to the chemical composition of particulate phase smoke. Seventy-five selected compounds were monitored for the comparison of particulate phase smoke of a commercial full-flavored (FF) cigarette with three different moisture contents at 7.8%, 14.5% and 20.4%, respectively. It was demonstrated that the smoke of a dry cigarette is richer in lower molecular mass compounds than a regular cigarette. On the other hand, the smoke of a moist cigarette is richer in higher molecular mass compounds than a regular cigarette. To maximize the influence of cigarette moisture to the chemical composition, a separate set of measurements were done using only the first three puffs of smoke. The accumulation of moisture in the tobacco column of a burning cigarette may influence the smoke composition, as generated during burning. The differences between dry, regular and moist cigarettes were more obvious for the first three puffs.
- Accesso libero
Pagine: 192 - 203
The manuscript presents results from a collaborative study by 15 different laboratories using two different methods to determine tobacco specific nitrosamines (TSNAs) in tobacco and was performed under the auspices of the Tobacco Science Research Conference Analytical Methods Committee (TSRC-AMC). Although it is apparent that some of the laboratories failed to follow the provided protocols, both methods proved robust for determining TSNAs in a variety of different tobacco types. Twelve laboratories extracted the tobacco sample using an alkaline-methylene chloride extraction (Method 1) and nine used a buffer to extract the tobacco sample (Method 2). Six laboratories performed both methods. All participants used gas chromatography (GC) to separate the TSNAs and chemiluminescence detection. Method 1 used N-hexyl-N-nitroso-1-hexanamine (NDHA) as a surrogate (added prior to extraction) internal standard for quantitation. Method 2 used N-nitrosoguvacoline (NG) as the surrogate internal standard, NDHA as a chromatographic (added after extraction, prior to analysis) internal standard and external standard quantitation. After demonstrating that the average accuracy of both methods was at least about 92% through recovery studies, eight different tobacco types were analyzed in triplicate by each method. Means, reproducibility (precision between laboratories) and repeatability (precision within a laboratory) of results were determined for each method. After statistical analyses, it was established that both methods were capable of analyzing a variety of tobacco types and repeatability between methods was not significantly different. The limit of detection (LOD) and limit of quantitation (LOQ) were lower for Method 2 as compared to Method 1 when using the surrogate internal standard. Reproducibility variation, analyzed as the coefficient of variation, was 6% lower for Method 2 vs. Method 1 for N-nitrosonornicotine (NNN) and directionally 12% lower for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Method 2 using NDHA as the chromatographic internal standard has been recommended by the TSRC-AMC for use as a reference method. However, Method 1 using NDHA as surrogate internal standard is favored by four of the study participants because of lower chemical and material costs and higher sample throughput.