The pyrolysis of cigarette paper under the conditions that simulate cigarette smouldering and puffing

The combustion properties and pyrolysis behavior of cigarette paper under the pyrolysis conditions of cigarette smouldering were investigated by micro-scale combustion calorimetry (MCC), thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG-FTIR), respectively. MCC results demonstrated that the combustion and pyrolysis behavior are influenced by heating rate obviously. TG-FTIR results illustrated that the composition of the gaseous products were mainly composed of CO₂, H₂O carbonyl compounds, CO, and methanol. Flash pyrolysis experiment in combination with high performance liquid chromatography (FPy-HPLC) was used to study the pyrolytic formation of eight carbonyl compounds (i.e., formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone, and butyraldehyde) during the pyrolysis of cigarette paper under the pyrolysis conditions of cigarette puffing. Moreover, the solid char formed after the flash pyrolysis experiments were studied by X-ray photoelectron spectroscopy (XPS). It had been found that the pyrolysis temperature influenced the formation of carbonyl compounds and the composition of char greatly.     

The kinetics of tobacco pyrolysis

When tobacco is pyrolysed under non-isothermal flow conditions in an inert atmosphere, variation of the inert gas or its space velocity has only a minor effect on the profiles of formation rate versus temperature for seven product gases. Thus, mass transfer processes between the tobacco surface and the gas phase are very rapid, and the products are formed at an overall rate which is determined entirely by that of the chemical reactions.The effect of radical chain inhibitors (nitrogen oxides) on the pyrolysis is complex because of the resultant oxidation. Nevertheless, no evidence was found for the occurrence of radical chain reactions in the gas phase. A small proportion (less than 10%) of all the gases monitored are formed by homogeneous decomposition of volatile and semi-volatile intermediate products, in the furnace used.At temperatures above about 600°C the reduction of carbon dioxide to carbon monoxide by the carbonaceous tobacco residue becomes increasingly important. However, when tobacco is pyrolysed in an inert atmosphere, only a small amount of carbon dioxide is produced above 600°C and consequently its reduction to carbon monoxide contributes only a small proportion to the total carbon monoxide formed above that temperature. The rate of the tobacco/carbon dioxide reaction is controlled by chemical kinetic rather than mass transfer effects. Carbon monoxide reacts with tobacco to a small extent.When the tobacco is pyrolysed in an atmosphere containing oxygen (9–21% v/v), some oxidation occurs at 200°C. At 250°C the combustion rate is controlled jointly by both kinetic and mass transfer processes, but mass transfer of oxygen in the gas phase becomes increasingly important as the temperature is increased, and it is dominant above 400°C. About 8% of the total carbon monoxide formed by combustion is lost by its further oxidation.The results imply that inside the combustion coal of a burning cigarette the actual reactions occurring are of secondary importance, the rate of supply of oxygen being the dominant factor in determining the combustion rate and heat generation. In contrast, in the region immediately behind the coal, where a large proportion of the products which enter mainstream smoke are formed by thermal decomposition of tobacco constituents, the chemistry of the tobacco substrate is critical, since the decomposition kinetics are controlled by chemical rather than mass transfer effects. tobacco substrate is critical. In addition, the heat release or absorption due to the pyrolytic reactions occurring behind the coal will depend on the chemical composition of the substrate. Thus, together with the differing thermal properties of the tobacco, the temperature gradient behind the coal should depend on the nature of the tobacco.     

Pyrolysis and combustion of tobacco in a cigarette smoking simulator under air and nitrogen atmosphere

A coupling between a cigarette smoking simulator and a time-of-flight mass spectrometer was constructed to allow investigation of tobacco smoke formation under simulated burning conditions. The cigarette smoking simulator is designed to burn a sample in close approximation to the conditions experienced by a lit cigarette. The apparatus also permits conditions outside those of normal cigarette burning to be investigated for mechanistic understanding purposes. It allows control of parameters such as smouldering and puff temperatures, as well as combustion rate and puffing volume. In this study, the system enabled examination of the effects of “smoking” a cigarette under a nitrogen atmosphere. Time-of-flight mass spectrometry combined with a soft ionisation technique is expedient to analyse complex mixtures such as tobacco smoke with a high time resolution. The objective of the study was to separate pyrolysis from combustion processes to reveal the formation mechanism of several selected toxicants. A purposely designed adapter, with no measurable dead volume or memory effects, enables the analysis of pyrolysis and combustion gases from tobacco and tobacco products (e.g. 3R4F reference cigarette) with minimum aging. The combined system demonstrates clear distinctions between smoke composition found under air and nitrogen smoking atmospheres based on the corresponding mass spectra and visualisations using principal component analysis.     

Patterns and kinetics of pyrolysis of tobacco under inert and oxidative conditions

The present work is part of a more extensive research carried out in Naples on cigarette combustion. Theoretical and modelling work highlighted the existence of a misdistribution of the gas flow across the cigarette cross-section, which results into locally variable conditions. As a consequence, oxygen-starving versus oxygen-rich conditions do establish in the pre-heat zone of the cigarette, where pyrolysis of cigarette components takes place. More specifically, oxygen-starving conditions should characterize the process of reaction front propagation in the inner part of the cigarette, close to its axis, while oxygen-rich conditions should establish at the cigarette periphery, close to the paper burn line.The present paper addresses the pattern and the kinetics of pyrolysis under inert and under oxidative conditions of three types of tobacco. The experimental work consists of non-isothermal thermogravimetric analysis at heating rates comprised between 5 and 20 °C/min and with different He–oxygen mixtures. Kinetic expressions for the rate of pyrolysis under inert and under oxidative conditions have been obtained for each ingredient investigated.Results, albeit obtained at sample heating rates smaller than those relevant to actual cigarette burning, highlight the profound differences arising under purely pyrolytic or oxy-pyrolytic conditions as regards the number of reaction steps, the rate, the temperature ranges and yields in solid versus gaseous products of thermal decomposition.The effect of inert/oxidative conditions on the chemical composition of the gaseous products of pyrolysis is discussed in a companion paper [O. Senneca, S. Ciaravolo, A. Nunziata, J. Anal. Appl. Pyrol. 78 (2007) 452].     

The vaporization of semi-volatile compounds during tobacco pyrolysis

Pyrolysis of tobacco, a complex biomass matrix, was investigated to further understand thermal decomposition processes that are accompanied by evaporation of relatively stable non-polymeric endogenous compounds. Pyrolysis of two types of tobacco, bright and burley were studied using thermo-gravimetry mass spectrometry (TG–MS) and field ionization mass spectrometry (FIMS) analyses. Tobacco contains biopolymers and many non-polymeric compounds. Unlike many biomass pyrolysis tars derived from wood or cellulose, tobacco pyrolysis tars can contain significant amounts of high molecular weight endogenous constituents such as waxes and terpenes that are transferred intact. The phenomenon of evaporation of high molecular weight non-polymeric compounds is illustrated by tobacco micro-sample pyrolysis in FIMS under vacuum (at a pressure of 10⁻⁴ Torr). These experiments indicate that the evaporation of relatively stable high molecular weight species occurs below about 220 °C generating 300 Da and higher molecular weight products; and, decomposition of tobacco biopolymers such as starch, cellulose, hemicellulose, lignin, and pectin occurs mostly at temperatures higher than 220 °C producing species mostly with molecular weight below 300 Da. Some of the high molecular weight compounds, such as stigmasterol (412 Da), α-tocopherol (430 Da), and solanesol (630 Da), were tentatively identified using the FIMS spectra.     

Pyrolysis behavior of pectin under the conditions that simulate cigarette smoking

In this paper, the formation mechanism of pyrolysis gases released during the pyrolysis of pectin under the conditions that simulate cigarette smouldering was investigated by thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG-FTIR). Moreover, the combustion behavior of pyrolysis gases was studied by micro-scale combustion calorimetry (MCC). TG-FTIR results illustrated that the composition of the gaseous products was mainly composed of CO₂, H₂O, CO, methanol, methane and carbonyl compounds. MCC results demonstrated that the combustion of pectin was mainly determined by the prolysis gases formed in the temperature range of 200-300 °C. Flash pyrolysis experiment in combination with high performance liquid chromatography (FPy-HPLC) was used to study the pyrolytic formation of eight carbonyl compounds (i.e. formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone and butyraldehyde) during the pyrolysis of pectin under the pyrolysis conditions of cigarette puffing. Results demonstrated that pyrolysis temperature influenced the formation of acetaldehyde, acrolein, propionaldehyde and butyraldehyde greatly, while nitrogen flow affected the generation of formaldehyde, acetone, crotonaldehyde and methyl ethyl ketone deeply.     

生物质焦制备条件对其燃烧反应特性的影响

在热重分析仪上,研究了生物质焦的制备条件对其燃烧反应特性的影响。生物质焦由闪速裂解技术制得,裂解温度为 748 K、773 K和823 K;原料含水质量分数为0、7.0%和11.3%。研究发现,生物质焦中挥发性物质的质量分数和H/C质量比随裂解温度的增加而降低,其燃烧反应性随裂解温度的增加而降低;与高裂解温度条件下制得的生物质焦相比,低裂解温度条件下制得的生物质焦具有较高的反应活化能和对燃烧温度更敏感。原料含水量对生物质焦的燃烧反应特性影响很小;但对高裂解温度条件下制得的生物质焦中的挥发性组分含量有较大的影响。简化的生物质焦本征燃烧反应幂函数动力学模型可以很好地描述其燃烧行为。     

Quantitative analysis of acetates in cigarette tobacco using solid-phase microextraction and gas chromatography-mass spectrometry

A method incorporating solid-phase microextraction (SPME) and gas chromatography-mass spectrometry for the headspace analysis of selected volatile organic compounds present in cigarette tobacco is developed and evaluated. Quantitative information on methyl, ethyl, n-propyl, isopropyl, isopropenyl, vinyl, and butyl acetates present in 29 different flavor variants (full, light, and ultra-light) of the top ten selling brands in the United States is presented. The concentrations of the various acetate analytes range from the low nanaogram to microgram levels per cigarette. Clear differences are observed in the concentrations of various acetates when comparing the levels in brands from different manufacturers. The SPME technique provides a method that allows high sample throughput, requires little sample preparation, and yields useful analytical information. High precision is obtained on multiple measurements of cigarettes from an individual pack, but lower precision levels are observed in general when comparing results obtained on the analysis of cigarettes from different packs of the same brand. The higher pack-to-pack variations may be due in part to product aging with a proportionate amount of evaporative loss of the relatively volatile acetates.     

The effects of sample preparation,pyrolysis and pyrolyzate transfer conditions on pyrolysis mass spectra

Two different biopolymers, bovine serum albumin and glycogen, were examined by pyrolysis-mass spectrometry under various experimental conditions. The parameters tested include the method of cleaning the pyrolysis wire, the choice of the sample solvent, the sample size, the temperature-time profile and the temperature of the mass spectrometric inlet system.In order to determine quantitatively the effects of changes in experimental conditions on reproducibility of the spectra, the differences observed between the pyrolysis mass spectra represented as numerical dissimilarity values.It is concluded that the long-term differences observed are only partly explained by fluctuations in the conditions studied. However, it appears feasible to define a set of standard conditions with respect to the production of the pyrolyzate which should afford a reasonable degree of interlaboratory reproducibility.     

The formation of Pt-Ru alloy nanoparticles in a carbon matrix under IR pyrolysis conditions

Nanosized Pt-Ru alloy and Pt₁₃Ru₂₇ intermetallic compound particles dispersed in a carbon matrix were obtained for the first time directly during the preparation of the composite. The alloying of the Pt and Ru particles occurred at IR pyrolysis intensities corresponding to temperatures above 700°C over the whole homogeneity range of solid solutions based on platinum. Metallic nanoparticles were round-shaped (the mean size 6–8 nm) and had a narrow particle-size distribution.     

Microprobe sampling—Photo ionization-time-of-flight mass spectrometry for in situ chemical analysis of pyrolysis and combustion gases: Examination of the thermo-chemical processes within a burning cigarette

A microprobe sampling device (μ-probe) has been developed for in situ on-line photo ionization mass spectrometric analysis of volatile chemical species formed within objects consisting of organic matter during thermal processing. With this approach the chemical signature occurring during heating, pyrolysis, combustion, roasting and charring of organic material within burning objects such as burning fuel particles (e.g., biomass or coal pieces), lit cigarettes or thermally processed food products (e.g., roasting of coffee beans) can be investigated. Due to its dynamic changes between combustion and pyrolysis phases the cigarette smoking process is particularly interesting and has been chosen as first application. For this investigation the tip of the μ-probe is inserted directly into the tobacco rod and volatile organic compounds from inside the burning cigarette are extracted and real-time analyzed as the glowing front (or coal) approaches and passes the μ-probe sampling position. The combination of micro-sampling with photo ionization time-of-flight mass spectrometry (PI-TOFMS) allows on-line intrapuff-resolved analysis of species formation inside a burning cigarette. Monitoring volatile smoke compounds during cigarette puffing and smoldering cycles in this way provides unparalleled insights into formation mechanisms and their time-dependent change. Using this technique the changes from pyrolysis conditions to combustion conditions inside the coal of a cigarette could be observed directly. A comparative analysis of species formation within a burning Kentucky 2R4F reference cigarette with μ-probe analysis reveals different patterns and behaviors for nicotine, and a range of semi-volatile aromatic and aliphatic species.     

Gas-phase pyrolysis of 2,2,3,3-tetramethylbutane using a wall-less reactor

The pyrolysis of 2,2,3,3-tetramethylbutane (TMB) has been studied using the wall-less reactor. Under homogeneous conditions up to 670°C, the activation energy is 43.2 kcal/mol and log A is 10.70. The products are 2-methylpropene, hydrogen, propene, 2-methyl-2-butene, ethane, ethene, methane, neopentane, and 2,3-dimethyl-2-butene in order of abundance. Addition of toluene, cyclopentadiene, or nitrous oxide to the system increases both the activation energy and the A factor; whereas oxygen decreases both the activation energy and the A factor. Incorporation of stainless-steel rods to provide surface has only a modest effect upon the rate. In view of this evidence, it appears that the homogeneous pyrolysis of TMB at higher pressures is a chain reaction under the described conditions.     

The impact of cigarette/e‐cigarette vapour on simulated pulmonary surfactant monolayers under physiologically relevant conditions

Deviation in pulmonary surfactant structure–function activity can impair airway patency and lead to respiratory disorders. This novel study aims to evaluate the influence cigarette/e‐cigarette vapour has on model surfactant films located within a simulated pulmonary environment using a lung biosimulator. Chromatographic analysis confirmed that nicotine levels were consistent with the sampling regimen employed. On exposure to smoke vapour, Langmuir isotherms exhibited condensed character and a significant reduction in maximum surface pressure was noted in all cases. Langmuir isocycles, reflective of the human breathing cycle, demonstrated condensed character on smoke vapour delivery. A reduction in the maximum surface pressure was clear only in the case of cigarette vapour application. The components of cigarette vapour can cause oxidative damage to pulmonary surfactant and impair recycling. Neutral nicotine molecules can weaken the structure of the monolayer and cause destabilisation. A protective effect was evident in the case of repeated surfactant compression – relaxation cycles (i.e. the ability to reduce the surface tension term was impaired less), demonstrating a likely innate biological defensive mechanism of the lung. E‐cigarette vapour appeared to have a reduced impact on surfactant performance, which may hold value in harm reduction over the longer term. Copyright © 2017 John Wiley & Sons, Ltd.     

Fractionation of cadmium in tobacco and cigarette smoke condensate using XANES and sequential leaching with ICP-MS/MS

Analytical and Bioanalytical Chemistry - Fractionation data for cadmium in tobacco products, as obtained by sequential leaching of cadmium species with ICP-MS/MS analysis, and separately by X-ray...     

Analysis of five active ingredients of Er-Zhi-Wan,a traditional Chinese medicine water-honeyed pill,using the biopharmaceutics classification system

Er-Zhi-Wan (EZW) is a traditional Chinese medicine with many clinical applications and used as a health product in East Asia. Five active ingredients (salidroside, specnuezhenide, nuezhenoside, luteolin, and oleanolic acid) were screened out from EZW to develop an in vitro rapid evaluation method for the classification of in vivo drug absorption behavior by biopharmaceutics classification system (BCS). Ultra-performance liquid chromatography was used for quantitative analysis. Solubility and permeability were assayed by equilibrium solubility and multiple models: everted rat intestinal sac model, cultured Caco-2 cells, octanol–water partition coefficient (LogP) method. The BCS properties of drugs were predicted using software applications, and the correlations of measured and predicted values of factors affecting oral drug absorption were calculated. The results were verified by measuring the absolute bioavailability of the active ingredients. Salidroside, specnuezhenide, and nuezhenoside were classified as BCS class III drugs, and luteolin was classified as a BCS class III/I drug because of the difference in LogP and intestinal permeability. Oleanolic acid was classified as a BCS class II/IV drug in acidic media and BCS class I/III drug in other media. Overall, EZW may be classified as a BCS class III drug, and permeability was identified as the primary factor limiting absorption. The results provide a novel method for the evaluation of the in vivo absorption of oral traditional Chinese medicines.     

Preparation and evaluation of Ibuprofen solid dispersion systems with kollidon particles using a pulse combustion dryer system

Solid dispersions (SDs) of ibuprofen (IBU) were prepared with four carriers: Kollidon 25, Kollidon 30, Kollidon VA64, and Kollidon CL, using a newly developed pulse combustion dryer system, HYPULCON. Physicochemical properties of the SDs obtained were investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), scanning electron microscope (SEM), and Fourier transformation IR spectroscopy (FT-IR). Powder X-ray diffraction (PXRD) showed that the crystal diffraction peaks of IBU in SDs disappeared completely, and in differential scanning calorimetry (DSC) curves, the endothermic peaks of IBU in SDs were not observed. Fourier transformation IR spectroscopy (FT-IR) proved that interactions between the drug and carrier existed. These findings demonstrated that IBU changed to an amorphous form in the SDs with the four carriers using the pulse combustion dryer system. The dissolution property of IBU in the SDs was markedly enhanced. The dissolution test showed that after 5 min of dissolution, the concentrations of IBU in the SDs with Kollidon CL as the carrier was 43.81 mug/ml, corresponding to 13.0 times that of pure IBU. So, it is demonstrated that the pulse combustion dryer system is very useful for preparing SDs of IBU with Kollidon of different grades as carriers.     

Design of a microprocessor-controlled automated injection system for the analysis of gas phase cigarette smoke using glass capillary columns

An automatic injection system for the analysis of gas phase smoke has been designed and evaluated using the microprocessor-controlled Hewlett-Packard 5830 gas chromatograph. The cryogenic preconcentration trap was constructed from relatively inexpensive and readily available materials. It was determined that the use of the preconcentration trap, as opposed to condensing the smoke on the head of the cold (-50°C) chromatographic column, significantly enhanced the resolution of the more volatile gas phase components. Data are presented which illustrate the injection system characteristics. In addition, chromatograms of gas phase smoke are presented which demonstrate the effectiveness of this technique.     

Modeling of acetylene pyrolysis under steel vacuum carburizing conditions in a tubular flow reactor

In the present work, the pyrolysis of acetylene was studied under steel vacuum carburizing conditions in a tubular flow reactor. The pyrolysis temperature ranged from 650 degrees C to 1050 degrees C. The partial pressure of acetylene in the feed mixture was 10 and 20 mbar, respectively, while the rest of the mixture consisted of nitrogen. The total pressure of the mixture was 1.6 bar. A kinetic mechanism which consists of seven species and nine reactions has been used in the commercial computational fluid dynamics (CFD) software Fluent. The species transport and reaction model of Fluent was used in the simulations. A comparison of simulated and experimental results is presented in this paper.