Organic particulate matter formation at varying relative humidity using surrogate secondary and primary organic compounds with activity corrections in the condensed phase obtained using a method based on the Wilson equation

International audienceSecondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N·2p) approach. The N·2p approach neglects: 1) variation of activity coefficient (?i) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N·2p)?, MW ,? approach (? is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of ?i and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,i° (atm). To facilitate adoption of the (N·2p)?, MW, ? approach in large-scale models, this study also develops CP-Wilson.1, a group-contribution ?i-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting ?i values to predictions from UNIFAC. The (N·2p)?,MW, ? approach is applied (using CP-Wilson.1) to several real ?-pinene/O3 chamber cases for high reacted hydrocarbon levels (?HC?400 to 1000 ?g m?3) when relative humidity (RH) ?50%. Good agreement between the chamber and predicted results is obtained using both the (N·2p)?, MW, ? and N·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical ?-pinene/O3 case at ?HC=30 ?g m?3 and RH=50%, the (N·2p)?, MW, ? approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N·2p approach. Adoption of the (N·2p)?, MW, ? approach using reasonable lumped structures for SOA and POA compounds is recommended for ambient PM modeling

Identification of Cytotoxic Flavor Chemicals in Top-Selling Electronic Cigarette Refill Fluids.

We identified the most popular electronic cigarette (EC) refill fluids using an Internet survey and local and online sales information, quantified their flavor chemicals, and evaluated cytotoxicities of the fluids and flavor chemicals. "Berries/Fruits/Citrus" was the most popular EC refill fluid flavor category. Twenty popular EC refill fluids were purchased from local shops, and the ingredient flavor chemicals were identified and quantified by gas chromatography-mass spectrometry. Total flavor chemical concentrations ranged from 0.6 to 27.9 mg/ml, and in 95% of the fluids, total flavor concentration was greater than nicotine concentration. The 20 most popular refill fluids contained 99 quantifiable flavor chemicals; each refill fluid contained 22 to 47 flavor chemicals, most being esters. Some chemicals were found frequently, and several were present in most products. At a 1% concentration, 80% of the refill fluids were cytotoxic in the MTT assay. Six pure standards of the flavor chemicals found at the highest concentrations in the two most cytotoxic refill fluids were effective in the MTT assay, and ethyl maltol, which was in over 50% of the products, was the most cytotoxic. These data show that the cytotoxicity of some popular refill fluids can be attributed to their high concentrations of flavor chemicals

High concentrations of flavor chemicals are present in electronic cigarette refill fluids.

We characterized the flavor chemicals in a broad sample of commercially available electronic cigarette (EC) refill fluids that were purchased in four different countries. Flavor chemicals in 277 refill fluids were identified and quantified by gas chromatography-mass spectrometry, and two commonly used flavor chemicals were tested for cytotoxicity with the MTT assay using human lung fibroblasts and epithelial cells. About 85% of the refill fluids had total flavor concentrations >1 mg/ml, and 37% were >10 mg/ml (1% by weight). Of the 155 flavor chemicals identified in the 277 refill fluids, 50 were present at ≥1 mg/ml in at least one sample and 11 were ≥10 mg/ml in 54 of the refill fluids. Sixty-one% (170 out of 277) of the samples contained nicotine, and of these, 56% had a total flavor chemical/nicotine ratio >2. Four chemicals were present in 50% (menthol, triacetin, and cinnamaldehyde) to 80% (ethyl maltol) of the samples. Some products had concentrations of menthol ("Menthol Arctic") and ethyl maltol ("No. 64") that were 30 times (menthol) and 100 times (ethyl maltol) their cytotoxic concentration. One refill fluid contained cinnamaldehyde at ~34% (343 mg/ml), more than 100,000 times its cytotoxic level. High concentrations of some flavor chemicals in EC refill fluids are potentially harmful to users, and continued absence of any regulations regarding flavor chemicals in EC fluids will likely be detrimental to human health

Eugenol, Menthol and other Flavour Chemicals in Kreteks and ‘white’ cigarettes purchased in Indonesia

Background Flavoured tobacco products are not restricted in Indonesia, a country with about 68 million adults who smoke. Most use clove-mixed tobacco cigarettes (‘kreteks’); non-clove (‘white’) cigarettes are also available. Although the use of flavour chemicals has been identified by WHO as promoting tobacco use, little has been reported for Indonesia about the levels of flavourants in either kreteks or ‘white cigarettes’. Methods 22 kretek brand variants and nine ‘white’ cigarette brand variants were purchased in Indonesia during 2021/2022; one of the kretek packs contained three colour-coded variants, giving a total sample number of 24 for the kreteks. Chemical analyses gave the mg/stick (=mg/(filter+rod)) values for 180 individual flavour chemicals that included eugenol (a clove-flavoured compound), four other clove-related compounds and menthol. Results Eugenol was present at significant levels in all 24 kreteks (2.8–33.8 mg/stick), but was essentially absent in all of the cigarettes. Menthol was present in 14 of 24 kreteks, with levels ranging from 2.8 to 12.9 mg/stick, and in five of the nine cigarettes, with levels ranging from 3.6 to 10.8 mg/stick. Other flavour chemicals were also found in many of the kretek and cigarette samples. Conclusions In this small sample, we found numerous variations of flavoured tobacco products offered by multinational and national companies in Indonesia. Given the body of evidence that flavours make tobacco products more appealing, regulation of clove-related compounds, menthol and other flavour chemicals should be considered in Indonesia

Ethyl Maltol, Vanillin, Corylone and other Conventional Confectionery-related Flavour Chemicals Dominate in Some E-cigarette Liquids Labelled ‘tobacco’ flavoured

Background The increased popularity of electronic cigarettes (e-cigarettes) has been linked to the abundance of flavoured products that are attractive to adolescents and young adults. In the last decade, e-cigarette designs have evolved through four generations that include modifications in battery power, e-cigarette liquid (e-liquid) reservoirs and atomiser units. E-liquids have likewise evolved in terms of solvent use/ratios, concentration and number of flavour chemicals, use of nicotine salts and acids, the recent increased use of synthetic cooling agents and the introduction of synthetic nicotine. Our current objective was to evaluate and compare the evolving composition of tobacco-flavoured e-liquids over the last 10 years. Methods Our extensive database of flavour chemicals in e-liquids was used to identify trends and changes in flavour chemical composition and concentrations. Results Tobacco-flavoured products purchased in 2010 and 2011 generally had very few flavour chemicals, and their concentrations were generally very low. In tobacco-flavoured refill fluids purchased in 2019 and Puff Bar Tobacco e-cigarettes, the total number and concentration of flavour chemicals were higher than expected. Products with total flavour chemicals \u3e10 mg/mL contained one to five dominant flavour chemicals (\u3e1 mg/mL). The most frequently used flavour chemicals in tobacco e-liquids were fruity and caramellic. Conclusions There is a need for continuous surveillance of e-liquids, which are evolving in often subtle and harmful ways. Chemical constituents of tobacco flavours should be monitored as they clearly can be doctored by manufacturers to have a taste that would appeal to young users

\u27Menthol-Plus’: a Major Category of Cigarette Found Among ‘Concept’ Descriptor Cigarettes from Mexico

Background Tobacco companies are offering cigarettes with ‘concept’ descriptor names that suggest sensation and/or flavour properties (eg, Marlboro ‘Velvet Fusion’). Little has been known about the identities and levels of flavour chemicals in such cigarettes. Methods Thirty-three filter cigarette variants from 27 packs (including two sampler packs with four variations each) from Canada and Mexico were analysed (rod + filter) for 177 flavour chemicals plus triacetin, a filter plasticiser and possible flavourant. Five brands of US mentholated filter cigarettes were also analysed. Results Twenty-seven of the 33 cigarettes (all were Mexican variants) were categorised as ‘menthol-plus’: significant menthol (3.0–11.9 mg/cigarette), plus varying amounts (0.32–3.4 mg/cigarette) of total other flavour chemicals (TOFCs) (excludes triacetin). For 10 of the 27, TOFCs \u3e1.0 mg/cigarette. For 7 of the 27, the TOFCs profile was categorised as containing total fruit flavour compounds (TFFCs) \u3e1.0 mg/cigarette. One Mexican variant was categorised as ‘menthol-only’ (TOFCs ≤0.15 mg/cigarette). All menthol-plus and menthol-only cigarettes contained one or two optional-crush capsules in their filters (crushed prior to analysis). All five Canadian brand variants were ‘non-flavoured’. All five US brand variants were ‘menthol-only’. Conclusions All but one of the ‘concept’ descriptor cigarettes from Mexico were ‘menthol-plus’. While the Canadian cigarettes complied with Canada’s flavour chemical ban, concept descriptors on the packs may increase appeal. Given the scale of the problem posed by menthol alone, health officials seeking to decrease the appeal of smoked tobacco should examine the extent to which ‘concept descriptor’ cigarettes using ‘menthol-plus’ flavour profiling together with artful descriptors are furthering the problem of smoked tobacco

Identification and quantification of gaseous organic compounds emitted from biomass burning using two-dimensional gas chromatography/time-of-flight mass spectrometry

The current understanding of secondary organic aerosol (SOA) formation within biomass burning (BB) plumes is limited by the incomplete identification and quantification of the non-methane organic compounds (NMOCs) emitted from such fires. Gaseous organic compounds were collected on sorbent cartridges during laboratory burns as part of the fourth Fire Lab at Missoula Experiment (FLAME-4), with analysis by two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC/TOFMS). The sensitivity and resolving power of GC×GC/TOFMS allowed the acquisition of the most extensive data set of BB NMOCs to date, with measure ments for 722 positively or tentatively identified compounds. Estimated emission factors (EFs) are presented for these compounds for burns of six different vegetative fuels, including conifer branches, grasses, agricultural residue, and peat. The number of compounds detected from individual burns ranged from 129 to 474, and included extensive isomer groups. For example, 38 monoterpene isomers were observed in the emissions from coniferous fuels; the isomeric ratios were found to be consistent with those reported in relevant essential oils, suggesting that the composition of such oils may be very useful when predicting fuel-dependent terpene emissions. Further, eleven sesquiterpenes were detected and tentatively identified, providing the first reported speciation of sesquiterpenes in gas-phase BB emissions. The calculated EFs for all measured compounds are compared and discussed in the context of potential SOA formation

Identification and quantification of gaseous organic compounds emitted from biomass burning using two-dimensional gas chromatography–time-of-flight mass spectrometry

The current understanding of secondary organic aerosol (SOA) formation within biomass burning (BB) plumes is limited by the incomplete identification and quantification of the non-methane organic compounds (NMOCs) emitted from such fires. Gaseous organic compounds were collected on sorbent cartridges during laboratory burns as part of the fourth Fire Lab at Missoula Experiment (FLAME-4) and analyzed by two-dimensional gas chromatography-time-of-flight mass spectrometry (GC x GC-ToFMS). The sensitivity and resolving power of GC x GC-ToFMS allowed the acquisition of the most extensive data set of BB NMOCs to date, with measurements from 708 positively or tentatively identified compounds. Estimated emission factors (EFs) are presented for these compounds for burns of six different vegetative fuels, including conifer branches, grasses, agricultural residue, and peat. The number of compounds meeting the peak selection criteria ranged from 129 to 474 among individual burns, and included extensive isomer groups. For example, 38 monoterpene isomers were observed in the emissions from coniferous fuels; the isomeric ratios were found to be consistent with those reported in relevant essential oils, suggested that the composition of such oils may be very useful when predicting fuel-dependent terpene emissions. Further, 11 sesquiterpenes were deteched and tentatively identified, providing the first reported speciation of sesquiterpenes in gas-phase BB emissions. The calculated EFs for all measured compounds are compared and discussed in the context of potential SOA formation

A burst search for gravitational waves from binary black holes

Compact binary coalescence (CBC) is one of the most promising sources of gravitational waves. These sources are usually searched for with matched filters which require accurate calculation of the GW waveforms and generation of large template banks. We present a complementary search technique based on algorithms used in un-modeled searches. Initially designed for detection of un-modeled bursts, which can span a very large set of waveform morphologies, the search algorithm presented here is constrained for targeted detection of the smaller subset of CBC signals. The constraint is based on the assumption of elliptical polarisation for signals received at the detector. We expect that the algorithm is sensitive to CBC signals in a wide range of masses, mass ratios, and spin parameters. In preparation for the analysis of data from the fifth LIGO-Virgo science run (S5), we performed preliminary studies of the algorithm on test data. We present the sensitivity of the search to different types of simulated CBC waveforms. Also, we discuss how to extend the results of the test run into a search over all of the current LIGO-Virgo data set.Comment: 12 pages, 4 figures, 2 tables, submitted for publication in CQG in the special issue for the conference proceedings of GWDAW13; corrected some typos, addressed some minor reviewer comments one section restructured and references updated and correcte