Fate of pyrazines in the flavored liquids of e-cigarettes

Abstract

Popularity of electronic cigarettes (ECIGs) has increased tremendously among young people, in part due to flavoring additives in ECIG liquids. Pyrazines are an important class of these additives, and their presence in tobacco cigarettes has been correlated with increased acceptability of smoking among smokers and bystanders. Pyrazine use by the tobacco industry is therefore thought to encourage smoking. However, the extent of transfer of pyrazines present in the liquid to aerosols upon vaping remains unclear. We present a simple analytical method to quantify six pyrazine derivatives in liquids and aerosols of ECIGs that allows the isolation of pyrazines from interfering compounds, like nicotine. Standard pyrazine solutions and commercial ECIG samples of different brands and flavors were tested for their pyrazine content in the liquids and in the generated aerosols from these solutions. Testing on ECIG commercial liquids revealed a heterogeneous distribution in the levels and types of pyrazines, with acetyl and alkyl pyrazines present in more than 70% of the samples. This method confirmed that pyrazine additives are common in ECIG and that labels do not usually reflect the type and quantity of pyrazines in the liquid. Pyrazines were not correlated with the nicotine content or the brand of the liquid. The aerosols showed similar pyrazine profiles to their corresponding liquids. The efficiency of transfer of pyrazines into the particle phase was approximately 46%. Therefore, addition of pyrazines to ECIGs should be regulated, because they act synergistically with nicotine to increase product appeal, ease smoking initiation, and discourage cessation.

Vaped Humectants in E-Cigarettes Are a Source of Phenols

“…The introduced method separates phenolic compounds from the matrix due to the selective solubility of the analytes. A similar approach was previously reported by our group for analyzing nicotine and pyrazine in ECIG liquids and aerosols. , …”

“…A similar approach was previously reported by our group for analyzing nicotine and pyrazine in ECIG liquids and aerosols. 36,37 The literature has shown that the oxidation and thermal degradation of the main liquid components (PG and VG) led to the formation of carbonyl compounds, radicals, ROS, and other compounds. 38−40 Per contra, the formation of other families of toxicants, like aryl compounds, could be attributed to the addition reactions of radicals or unsaturated hydrocarbon intermediates.…”

Electronic nicotine delivery system design and aerosol toxicants: A systematic review

“…Uchiyama et al [106] observed large variations in carbonyl concentrations between and within unnamed devices. El-Hage et al [107] reported the transfer of pyrazines, a class of flavoring compounds, from eliquid to aerosol. Rawlinson et al [108] identified the chemical profiles of aerosols generated from 4 e-liquids contained between 30-90 compounds mostly characterized as "unknown" exceeding the 5 ng/puff threshold which may include PAHs.…”

Semibiocatalytic Approach toward Regioisomerically Enriched Ethyl Dimethylpyrazines Important in Flavor Industries

“…Among the many AlkPyrs, ethyl-dimethylpyrazines (EDMPs) are the most potent odorants (perceived as roasty and sweet) and generate a broad market demand. The 235- and 325-EDMP isomers ( 7 and 8 ) (Figure ) contribute to the desirable taste of tea − and are also used as flavoring agents, food additives, fragrances, and added ingredients in cigarettes; related AlkPyrs are found in e-cigarettes . Also, the commercially available mixtures of 7 and 8 were chromatographically separated to show that each distinctly affected the behavioral response of fire ants in an electroantennogram study .…”

“…The 235and 325-EDMP isomers (7 and 8) (Figure 1) contribute to the desirable taste of tea 27−29 and are also used as flavoring agents, food additives, fragrances, 30 and added ingredients in cigarettes; 31 related AlkPyrs are found in e-cigarettes. 32 Also, the commercially available mixtures of 7 and 8 were chromatographically separated to show that each distinctly affected the behavioral response of fire ants in an electroantennogram study. 33 Given the broad chemosensory application of EDMPs, several accounts highlight industrial syntheses and separation of these commodity compounds to address production bottlenecks.…”