Christopher Wright

Multivariate analysis of mainstream tobacco smoke particulate phase by headspace solid-phase micro extraction coupled with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOFMS) was developed and applied to evaluate profiles of volatile compounds present in mainstream tobacco smoke particulate matter trapped on glass fiber filters. Six SPME fibers were tested for the extraction capacities toward selected compounds, showing the best results for the polyacrylate fiber. The optimization of the extraction conditions was carried out using multivariate response surface methodology. Two cigarette types differing in a filter design were analyzed using optimized conditions. A template was built in order to generate comprehensive chemical information, which conceded obtaining consistent information across 24 chromatograms. Principal component analysis (PCA) allowed a clear differentiation of the studied cigarette types. Fisher ratio analysis allowed identification of compounds responsible for the chemical differences between the cigarette samples. Of the selected 143 most important ones, 134 analytes were reduced by the active carbon filter, while for nine, classical cellulose acetate filter was more efficient.

Analysis of mainstream tobacco smoke particulate phase using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

Comprehensive 2D GC coupled to time-of-flight mass spectrometry was applied for the characterization of the particulate phase of mainstream tobacco smoke particulate. Five 3R4F research cigarettes were smoked on a rotary smoking machine under standardized conditions, total particular matter was collected on Cambridge filter pads and extracted using methanol-based liquid extraction and dynamic headspace (DHS) approaches. Automated peak finding and mass spectral deconvolution combined with scripting and manual revision of library hits were used to evaluate the library search results. The revised peak table contained nearly 1800 individual compounds for the DHS sample and over 900 for the solvent extracted sample. These methods of extraction were shown to be complementary, leading to only 11% of repeated analytes, and their combination gave rise to a list of almost 2500 individual compounds.

Determination of total arsenic and arsenic speciation in tobacco products: from tobacco leaf and cigarette smoke

The efficiency of a sequential extraction procedure (leaching with water followed by extraction with driselase and sodium dodecylsulfate) was investigated for quantitative As speciation in cut tobacco by HPLC-ICP-MS. The total As concentration and size-exclusion HPLC-ICP-MS profiles obtained for the extracts were used to select optimal extraction conditions as a trade-off between As extraction efficiency and preservation of compound identity. Leaching the cut tobacco (taken from 3R4F Kentucky research reference cigarettes) with water by either sonication in a water bath for 2 h or microwave-assisted extraction (MAE) at 50 W (50 °C) for only 10 min enabled approximately 42% of the total As in the solid to be extracted. Using anion-exchange HPLC with ICP-MS detection, 89% of the total water-soluble As was, for the first time, reported to be present as inorganic As. The instrumental limits of detection (3σ criterion) obtained for arsenite and arsenate by anion-exchange HPLC-ICP-MS were 10 and 50 ng kg−1 As, respectively. Using this hyphenated method, the presence of DMA and MMA as minor As species in the water-soluble fraction could also be detected. Complementary cation-exchange HPLC-ICP-MS analysis of unspiked extracts and extracts spiked with As standards pointed to the presence of arsenate (as a major As species) and DMA and MMA (as a minor As species). Interestingly, recent XANES results revealed that the cut tobacco contained almost exclusively As(V). Successive extractions with driselase and sodium dodecylsulfate (SDS) on the solid residue led to further extraction of approximately 13% and 8%, respectively, of As from the solid cut tobacco. The total As concentration in a homogenate of cut tobacco (from 3R4F Kentucky reference cigarettes) was found to be 318 ± 9 ng g−1 As (precision as SD, n = 3), as determined by microwave acid digestion followed by collision reaction cell ICP-MS (He mode) with standard addition calibration. The developed hyphenated MS methodology was used to study the speciation of As in water-soluble extracts of 3R4F mainstream smoke. These extracts were, for the first time, found to contain arsenite (As(III)), arsenate (As(V)) and an unidentified As-containing species. XANES analysis also reported a mixture of As(V) and As(III) in mainstream cigarette smoke condensate. The reduction of As(V) to As(III) during dynamic cigarette smoke formation can be explained by the overall smoke redox properties associated with the cigarette combustion process.

Assessment of novel tobacco heating product THP1.0. Part 3: Comprehensive chemical characterisation of harmful and potentially harmful aerosol emissions

ABSTRACT For a tobacco heating product (THP), which heats rather than burns tobacco, the emissions of toxicants in the aerosol were compared with those in cigarette smoke under a machine‐puffing regimen of puff volume 55 ml, puff duration 2 s and puff interval 30 s. The list of toxicants included those proposed by Health Canada, the World Health Organization Study Group on Tobacco Product Regulation (TobReg), the US Food and Drug Administration and possible thermal breakdown products. In comparison to the University of Kentucky 3R4F reference cigarette the toxicant levels in the THP1.0 emissions were significantly reduced across all chemical classes. For the nine toxicants proposed by TobReg for mandated reduction in cigarette emissions, the mean reductions in THP1.0 aerosol were 90.6–99.9% per consumable with an overall average reduction of 97.1%. For the abbreviated list of harmful and potentially harmful constituents of smoke specified by the US Food and Drug Administration Tobacco Products Scientific Advisory Committee for reporting in cigarette smoke (excluding nicotine), reductions in the aerosol of THP1.0 were 84.6–99.9% per consumable with an overall average reduction of 97.5%. HighlightsTHP1.0, which heats rather than burns tobacco, was compared with 3R4F cigarette.Harmful and potentially harmful constituents were measured in the aerosols and compared.Toxicants in the aerosol of THP1.0 were substantially lower than in 3R4F smoke.Reduction averaged 96.1 per cent for nine substances prioritised for lowering in cigarettes.Reduction averaged 96.8 per cent for 18 substances prioritised by the US FDA.

Assessing modified risk tobacco and nicotine products: Description of the scientific framework and assessment of a closed modular electronic cigarette

ABSTRACT Cigarette smoking causes many human diseases including cardiovascular disease, lung disease and cancer. Novel tobacco products with reduced yields of toxicants compared to cigarettes, such as tobacco‐heating products, snus and electronic cigarettes, hold great potential for reducing the harms associated with tobacco use. In the UK several public health agencies have advocated a potential role for novel products in tobacco harm reduction. Public Health England has stated that “The current best estimate is that e‐cigarettes are around 95% less harmful than smoking” and the Royal College of Physicians has urged public health to “Promote e‐cigarettes widely as substitute for smoking”. Health related claims on novel products such as ‘reduced exposure’ and ‘reduced risk’ should be substantiated using a weight of evidence approach based on a comprehensive scientific assessment. The US FDA, has provided draft guidance outlining a framework to assess novel products as Modified Risk Tobacco Products (MRTP). Based on this, we now propose a framework comprising pre‐clinical, clinical, and population studies to assess the risk profile of novel tobacco products. Additionally, the utility of this framework is assessed through the pre‐clinical and part of the clinical comparison of a commercial e‐cigarette (Vype ePen) with a scientific reference cigarette (3R4F) and the results of these studies suggest that ePen has the potential to be a reduced risk product. HighlightsDescription of a scientific framework to assess the risk profile of next generation products relative to cigarettes.Multi‐disciplinary studies comparing a commercial e‐cigarette (Vype ePen) with a scientific reference cigarette (3R4F).The test e‐cigarette aerosol is compositionally simpler, containing reduced levels of toxicants relative to cigarette smoke.Results from a range of multi‐disciplinary studies showed reduced responses for the test e‐cigarette relative to cigarettes.

Chemical characterisation of aerosols emitted by electronic cigarettes using thermal desorption–gas chromatography–time of flight mass spectrometry

A non-targeted analytical method, using thermal desorption-gas chromatography-time of flight mass spectrometry, to detect, identify and semi-quantify volatile and semi-volatile organic constituents of e-cigarette aerosols is presented. A heart-cutting process with a Deans Switch has been applied to avoid saturation of the mass analyser by high-abundance bulk components. Between 30 and 90 compounds were detected in four aerosol samples generated by e-cigarettes, depending on the added flavourings. The method analyses in a single 80mL, 3-second puff, GC-amenable compounds with volatilities ranging between those of propane (C3) and octacosane (C28) and abundance greater than approximately 5ng. Method sensitivity is suitable for the application of thresholds of toxicological concern for product assessment at an exposure threshold of 1.5μg per day. The method is compatible with the high-throughput screening of GC-amenable compounds in e-cigarette aerosols.

Headspace solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry for the analysis of aerosol from tobacco heating product

A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was developed and optimised to elucidate the volatile composition of the particulate phase fraction of aerosol produced by tobacco heating products (THPs). Three SPME fiber types were studied in terms of extraction capacity and precision measurements. Divinylbenzene polydimethylsiloxane appeared as the most efficient coating for these measurements. A central composite design of experiment was utilised for the optimization of the extraction conditions. Qualitative and semi-quantitative analysis of the headspace above THP aerosol condensate was carried out using optimised extraction conditions. Semi-quantitative analyses of detected constituents were performed by assuming that their relative response factors to the closest internal standard (itR) were equal to 1. Using deconvoluted mass spectral data (library similarity and reverse match >750) and linear retention indices (match window of ±15 index units), 205 peaks were assigned to individual compounds, 82 of which (including 43 substances previously reported to be present in tobacco) have not been reported previously in tobacco aerosol. The major volatile fraction of the headspace contained ketones, alcohols, aldehydes, alicyclic hydrocarbons alkenes, and alkanes. The method was further applied to compare the volatiles from the particulate phase of aerosol composition of THP with that of reference cigarette smoke and showed that the THP produced a less complex chemical mixture. This new method showed good efficiency and precision for the peak areas and peak numbers from the volatile fraction of aerosol particulate phase for both THP and reference cigarettes.

Accurate measurement of main aerosol constituents from heated tobacco products (HTPs): Implications for a fundamentally different aerosol.

ABSTRACT ISO 4387 Standard determines the main aerosol constituents (total particulate matter, water, nicotine, and nicotine‐free‐dry‐particulate matter, referred to as “tar”) in cigarette mainstream smoke (ISO, 2000). Heated Tobacco Products (also called Tobacco Heating Products or Heat‐not‐Burn Products) are designed to form aerosol by heating tobacco rather than burning like in combustible cigarettes. In this study we have evaluated the suitability of ISO 4387 Standard to be adapted for quantifying main aerosol constituents for HTP aerosol. HTP emissions have much higher levels of water and humectants (e.g., glycerol) in dynamic equilibria between gaseous and particulate phases. Several modifications to ISO 4387 Standard on aerosol collection were tested to improve the accuracy and reliability of aerosol capturing, with minimal deviation to the standard method. The proposed modifications are readily adoptable by laboratories already practicing the Standard for cigarette smoke analyses. Taking collectively with other available aerosol chemistry and biological results on HTPs in the literature, they show a fundamentally different aerosol in HTPs and call for category‐specific product standards and terminology. HighlightsHeated tobacco products (HTPs) are an emerging category for regulatory consideration.HTP emissions differ fundamentally to smoke in its aerosol constituents, e.g., water.The differences are considered and measures are tested to improve ISO 4387 Standard for HTP testing.Satisfactory assessment of nicotine‐free‐dry‐particulate‐matter for HTPs based on improved method is presented.The results add to the body of evidence demonstrating different physiochemical properties of HTP aerosol.

Comprehensive comparative compositional study of the vapour phase of cigarette mainstream tobacco smoke and tobacco heating product aerosol

A simple direct sample collection/dilution and introduction method was developed using quartz wool and Tenax/sulficarb sorbents for thermal desorption and comprehensive two-dimensional gas chromatography (TD-GC × GC) analyses of volatile organic compounds from vapour phase (VP) fractions of aerosol produced by tobacco heating products (THP1.0) and 3R4F mainstream tobacco smoke (MTS). Analyses were carried out using flame ionisation detection (FID) for semi-quantification and both low and high resolution time-of-flight mass spectrometry (LR/HR-TOFMS) for qualitative comparison and peak assignment. Qualitative analysis was carried out by combining identification data based on linear retention indices (LRIs) with a match window of ±10 index units, mass spectral forward and reverse library searches (from LR and HRTOFMS spectra) with a match factor threshold of >700 (both forward and reverse), and accurate mass values of ± 3 ppm for increased confidence in peak identification. Using this comprehensive approach of data mining, a total of 79 out of 85 compounds and a total of 198 out of 202 compounds were identified in THP1.0 aerosol and in 3R4F MTS, respectively. Among the identified analytes, a set of 35 compounds was found in both VP sample types. Semi-quantitative analyses were carried out using a chemical class-based external calibration method. Acyclic, alicyclic, aromatic hydrocarbons and ketones appeared to be prominent in 3R4F MTS VP, whereas larger amounts of aldehydes, ketones, heterocyclic hydrocarbons and esters were present in THP1.0 aerosol VP. The results demontsrate the capability and versatility of the method for the characterization and comparison of complex aerosol samples and highlighted the relative chemical simplicity of THP1.0 aerosol in comparison to MTS.

Optimized method for determination of 16 FDA polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke by gas chromatography–mass spectrometry

A gas chromatography–mass spectrometry (GC–MS) method was validated for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) from the FDA list of 93 harmful or potentially harmful constituents of mainstream cigarette smoke (MCS). Target analytes were extracted from total particulate matter using accelerated solvent extraction with a toluene/ethanol solvent mixture. Matrix artefacts were removed by two-step solid-phase extraction process. Three different GC–MS systems [GC–MS (single quadrupole), GC–MS/MS (triple quadrupole) and GC–HRMS (high resolution, magnetic sector)] using the same separation conditions were compared for the analysis of MCS of 3R4F Kentucky reference cigarettes generated under ISO and intense smoking regimes. The high mass resolution (m/∆m ≥ 10,000) and associated selectivity of detection by GC–HRMS provided the highest quality data for the target PAHs in MCS. Owing to the HR data acquisition mode enabling measurement of accurate mass, limits of quantification for PAHs were 5 to 15-fold lower for GC–HRMS than for GC–MS/MS and GC–MS. The presented study illustrates that the optimised sample preparation strategy followed by GC–HRMS analysis provides a fit-for-purpose and robust analytical approach allowing measurement of PAHs at (ultra)low concentrations in MCS. Furthermore, the study illustrates the importance and benefits of robust sample preparation and clean-up to compensate for limited selectivity when low-resolution MS is used.