The differences or equivalence of products depend on various sources of variability like analytical methods, manufacturing processes, agricultural practices and environmental conditions. In addition, the capacity to compare and discriminate accurately two products is impacted by the number of characteristics considered for the comparison. Previously, it has been shown that a comparison of two products can be performed using the critical difference (CD), because it takes into consideration both the variability of measurements and laboratories. However, some additional sources of variability need to be added in the comparison when products were not manufactured at the same period of time or in the same factory. Here, an extended critical difference is proposed including manufacturing process variability according to the number of samples and batches collected for each product. The general formula and specific cases corresponding to different situations (one vs two labs, short vs long periods of time, same vs different periods of time, one vs several batches) are given.
Although 2-nitropropane is a potentially harmful compound present in cigarette smoke, there are few fully-validated, modern methods to quantitate it in mainstream cigarette smoke. We developed an isotope dilution gas chromatography-tandem mass spectrometry (ID-GC-MS/MS) method for the detection of 2-nitropropane in mainstream cigarette smoke. The vapor fraction of mainstream cigarette smoke was collected in inert polyvinyl fluoride gas sampling bags and extracted with hexanes containing isotopically labeled internal standard, then purified and concentrated via solid-phase extraction using a normal phase silica adsorbent and a 100% dichloromethane eluant. This method is sensitive enough to measure vapor phase 2-nitro-propane concentrations in the nanogram range, with a 19 ng per cigarette method limit of detection. Product variability estimated from the analysis of 15 cigarette products yielded relative standard deviations ranging from 5.4% to 15.7%, and estimates of precision from two quality control products yielded relative standard deviations of 9.49% and 14.9%. Under the Health Canada Intense smoking regimen, 2-nitropropane in machine-generated mainstream smoke from 15 cigarette products ranged from 98.3 to 363 ng per cigarette.
Glucose and selected phosphate buffers have been reacted employing systematic variations in reaction temperature and time (150–160 °C for 60–90 min) to optimize the yield of acetol. This mixture was reacted further with NH4OH, systematically varying reaction conditions and reagent ratios to optimize pyrazine yield. The highest yield of pyrazine was obtained when 1 g of glucose was reacted with 25 mL of buffer at 150–160 °C for 60 min, which in turn was reacted with 1 mL of concentrated aqueous NH4OH at 120–130 °C for 17–18 h. Higher temperatures and higher concentrations of glucose caused a decrease in the yield of pyrazines. The addition of hydrolyzed tobacco-derived F1 protein as a secondary source of nitrogen increased the yield of pyrazines by 2–10% depending on F1 protein concentration. Furthermore, the addition of any α-hydroxyketone, similar in structure to acetol, as a pure reagent to the reaction mixture not only increased the yields of pyrazine by ranging from 25–100 % depending on the reagent concentration, but also significantly altered the qualitative and quantitative distribution of the pyrazines. With all of the reaction parameters examined (reaction time, temperature, reagent ratios, etc.) the most significant impacts on both pyrazine yield and distribution were noted when: 1) glucose was pre-reacted with buffer, 2) hydrolyzed F1 protein was added as a second nitrogen source, and 3) when pure α-hydroxyketones were employed as co-reagents. Use of these reaction parameters was found to dramatically shift the pyrazine distribution toward higher molecular weight resulting in a pyrazine array having more desirable physical and sensory attributes.
A screening method allowing the quantification of 24 aerosol constituents using gas chromatography-mass spectrometry has been developed to assess the aerosol chemistry of heat-not-burn tobacco products.
The aim of this method was to quantify phenol, o-cresol, m-cresol, p-cresol, catechol, resorcinol, hydroquinone, 1,3-butadiene, isoprene, benzene, acrylonitrile, toluene, pyridine, styrene, 1,2-propylene glycol, menthol, 2-furanmethanol, acrylamide, naphthalene, nicotine, acetamide, quinoline, triacetin, and glycerine in the aerosol emitted by heated tobacco products. The aerosol was generated by an electrically heated tobacco system (PMI’s Heated Tobacco System (THS 2.4)) with one single aerosol collection method, using the Health Canada smoking regimen and analyzed with two analytical methods.
The method was validated according to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use and the Association of Official Analytical Chemists guidelines.
A regression model based on a linear relationship between concentration and response ratio with a 1/x weighting factor was selected for phenol, o-cresol, m-cresol, p-cresol, 1,3-butadiene, isoprene, benzene, acrylonitrile, toluene, pyridine, styrene, 2-furanmethanol, acrylamide, naphthalene and acetamide. A quadratic regression model with a 1/x weighting factor was chosen for catechol, resorcinol, hydroquinone, 1,2-propylene glycol, menthol, nicotine, quinoline, triacetin and glycerine. Coefficients of variation for repeatability were determined between 7.9% and 17.8% and for intermediate precision between 8.1% and 19.9%.
The matrix effect of the heated tobacco aerosol extract was assessed by performing a recovery study, where the aerosol extracts were spiked at different concentrations for the compounds to be analyzed. In addition, the mainstream smoke from 3R4F reference cigarettes was analyzed, and results were compared with previously published studies. The method was successfully validated, providing data consistent with published data and it was shown to be selective, precise and accurate.
The objective of this work was to compare the nicotine content and yield of new very low nicotine content cigarettes (VLN™) to the top 100 cigarette brand styles in the United States. Nicotine in tobacco filler and nicotine in smoke were measured. On a dry weight basis, VLN™ cigarettes averaged 0.5 mg of nicotine/g tobacco as compared to 19.4 for the top 100 brand styles in the United States. On a cigarette basis, VLN™ cigarettes contained 0.27 mg of nicotine compared to 12 mg for the top brands. On an ISO smoke yield basis, VLN™ produced 0.03 mg nicotine/cig compared to 0.903 mg nicotine/cig for the leading brands. VLN™ cigarettes contained > 95% less nicotine on a per gram basis of tobacco or per cigarette basis than the top 100 brand styles in the U.S. VLN™ cigarettes yielded > 95% less nicotine in smoke than the top brand styles in the United States.
To study the effects of tobacco rod circumference on cigarette combustion status, cigarettes were made with three different circumferences of 24 mm, 20 mm, 17 mm and otherwise identical construction. Their combustion characteristics, including combustion coal volume, characteristic temperature distribution, heating rate, instantaneous burn rate, and yields of selected mainstream smoke chemicals, were systematically measured. The results indicated that the cigarettes with the lowest circumference of 17 mm showed higher combustion temperatures with a smaller coal volume. The maximum instantaneous burn rate was distinctly different for the three cigarettes, from 1.84 mm/s to 2.48 mm/s, when their circumference was reduced from 24 mm to 17 mm. The tobacco mass consumption per puff showed a negative trend when the circumference decreased. The majority of the chemical compounds (16 of 21) measured in mainstream smoke decreased when the circumference was reduced, except for formaldehyde, while the yields of the chemical compounds produced per weight of cut tobacco, consumed during puffing, showed an obverse trend.
The width of cut tobacco strands is an important indicator for physical parameters as well as for the smoking quality. In some countries, cut width helps to distinguish fine-cut tobacco and pipe tobacco and thus differentiates taxation rate. A new method for rapid measurement of the width of cut tobacco strands was developed based on digital image processing, because the method described in ISO 20193, though easy to implement in factories, proved time consuming and generated high testing costs. The essence of this method is to determine the statistic width of incisions. The straight-line segments represent the width of strands of cut tobacco, from which the determination of the width for randomly placed tobacco strands could be achieved. Five kinds of samples (‘ISO collaborative study samples 0.4 mm, 1.0 mm, 1.6 mm and 3.0 mm’ and ‘Guangdong baked 0.9 mm’) were used to study the comparability of the measurement results between the method presented in this work and the current ISO method. Results show that accuracy and repeatability are comparable. In addition, the testing efficiency of the method presented in this work appears to be higher than the current ISO method, and it is thus a promising alternative method for measuring the width of strands of cut tobacco.
Employment of 1-hydroxy-acetone as a carbon source and NH4OH as a source of base and nitrogen, has enabled arrays of pyrazines to be synthesized. Reaction conditions such as temperature, time, carbon/nitrogen mole ratios and pH were optimized to maximize the quantity of pyrazines, thereby providing the synthesis of at least 19–20 structurally different pyrazines. Addition of amino acids, selected aldehydes, and hydrolyzed tobacco-derived F1 protein has positively impacted the array of pyrazines from both qualitative and quantitative aspects. Results further showed that by changing the carbon source from 1-hydroxy-acetone to 1-hydroxy-2-butanone and/or 2-hydroxy-3-butanone, control of the type of pyrazines being synthesized could be realized in that the qualitative and quantitative distributions of the pyrazine array were shifted to higher molecular weight derivatives. A relatively large scale reaction (1.5 L) employing optimized parameters yielded > 2 g of a diverse array of pyrazines dominated by multiple dimethylpyrazine derivatives. While systematically varying reaction conditions and reagent mole ratios can predictably alter the distribution and yield of pyrazines, the two most overwhelmingly significant factors governing these two pyrazine product characteristics included the structure of the carbon source and the presence or absence of aldehydes and free amino acids.