E-cigarette Refill Liquids Research Articles

Comparative study of bisphenols in e-cigarette liquids: Evaluating fabric phase sorptive extraction, ultrasound-assisted membrane extraction, and solid phase extraction techniques

To address the under-researched risk of bisphenols (BPs) in e-cigarette liquids, comprehensive studies have been conducted to propose optimum sample preparation and analysis methods. To determine twelve BPs in refill liquids for e-cigarettes, three sample preparation methods based on distinct operational and working principles were employed. These included fabric phase sorptive extraction (FPSE), ultrasound-assisted solvent extraction of porous membrane-packed samples (UASE-PMS) and solid phase extraction (SPE) utilizing molecularly imprinted polymers (MIPs) technology. Each extraction method was combined with ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Key parameters of FPSE and UASE-PMS procedures were optimized. This optimization included selection of the FPSE membrane types, durations of extraction and the choice solvents. Comprehensive validation was conducted, demonstrating linearity across a range from 2 to 60 ng/mL for all BPs (BPS, BPA, BPF, BPE, BPB, BPC, BPZ, BPFL, BPBP, BPP, BPG and BPM). Determination coefficients were above 0.9913, signifying linear relationship. The limits of detection (LODs) were established below 0.90 ng/mL, while the limits of quantification (LOQs) were lower than 2.5 ng/mL. Notably, the method based on UASE-PMS was successfully applied to the analysis of refill liquids for e-cigarettes samples. A comparative analysis of the methods highlighted variances in precision, accuracy, and applicable aspects, such as adjustment of parameters, sample preparation time, cost, handling, availability and possible limitations. Three methods have been identified as suitable for analysing BPs in e-cigarette refill liquids, highlighting the necessity to examine their presence in these products.

HKUST−1 loaded Ag/TiO2 nanoparticles/graphene oxide composites modified sensor for sensitive detection of nicotine in electronic cigarette liquids

Electronic cigarettes (e-cigarette) have become more and more popular among young smokers in recent years. Nicotine, the main addictive component in cigarettes, is widely present in many e-cigarette. Assessing levels of nicotine is critical to the health of consumers and the development of tobacco industry. Herein, a novel electrochemical sensor based on Ag/TiO2 nanoparticles, metal–organic frameworks (MOFs) and graphene oxide (dual−NPs@HKUST−1/GO) nanocomposite was prepared for the rapid detection of nicotine in e-cigarette. The composites were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy, respectively. The results showed that the successfully synthesized composites have an average size of (20 ± 5) μm and excellent characterization properties. Under optimized conditions, the peak current response of nicotine with the differential pulse voltammetry showed a linear relationship in the range of 0.025–300 μM with a detection limit of 0.0145 μM. This newly developed dual−NPs@HKUST−1/GO-based sensor exhibited excellent selectivity, sensitivity and reproducibility for the accurate detection of nicotine. In addition, it also has excellent performance in detecting nicotine in actual e-cigarette refill liquids. The recoveries ranged from 88.6 % to 101.8 % in e-cigarette refill liquids, indicating good detection performance. This method provides a new concept for the detection of nicotine in the tobacco industry and clinical fields.

Synthetic Cooling Agents in Australian-Marketed E-cigarette Refill Liquids and Disposable E-cigarettes: Trends Follow the U.S. Market.

E-cigarettes are becoming increasingly popular in Australia, especially amongst the younger population. The synthetic cooling molecules WS-3 and WS-23 have been identified in e-cigarette products from the United States and Europe. The extent of inclusion of these synthetic coolants in Australian e-liquids is unknown, particularly in newer disposable e-cigarettes. E-cigarettes and e-liquids were purchased within Australia and anonymously donated by Australian users. Nicotine, WS-3, WS-23, and menthol were quantified in the e-liquids using gas chromatography-mass spectrometry (GC-MS). WS-23 and nicotine were detected in all of the disposable e-cigarettes with WS-23 often present in high concentrations. There was no correlation between cooling terms in the flavor name and the inclusion of cooling agents. Only three bottled e-liquids were found to contain WS-23 while none contained WS-3 above the limit of detection. Synthetic coolants were a common addition in disposable e-cigarettes while rarely added to e-liquid bottle refills. Their inclusion in these products is reflective of trends observed in United States and European e-cigarette products. The increase in synthetic cooling agents as components of e-liquids, particularly disposable e-cigarette devices, has been observed within Australian samples across a range of brands and flavors. WS-23 was present in every disposable e-cigarette analyzed in this study, often in relatively high concentrations. Its inhalational toxicology should be considered when evaluating the safety of these products.

Exposure to secondhand aerosol from electronic cigarettes at homes: A real-life study in four European countries

Electronic cigarette (e-cigarette) use emits potentially hazardous compounds and deteriorates indoor air quality. Home is a place where e-cigarettes may frequently be used amid its increasing prohibition in public places. This study assessed the real-life scenario of bystanders' exposure to secondhand e-cigarette aerosol (SHA) at home. A one-week observational study was conducted within the TackSHS project in four countries (Greece, Italy, Spain, and the United Kingdom) in 2019 including: 1) homes of e-cigarette users living together with a non-user/non-smoker; and 2) control homes with no smokers nor e-cigarette users. Indoor airborne nicotine, PM2.5, and PM1.0 concentrations were measured as environmental markers of SHA. Biomarkers, including nicotine and its metabolites, tobacco-specific nitrosamines, propanediol, glycerol, and metals were measured in participants' saliva and urine samples. E-cigarette use characteristics, such as e-cigarette refill liquid's nicotine concentration, e-cigarette type, place of e-cigarette use at home, and frequency of ventilation, were also collected. A total of 29 e-cigarette users' homes and 21 control homes were included. The results showed that the seven-day concentrations of airborne nicotine were quantifiable in 21 (72.4 %) out of 29 e-cigarette users' homes; overall, they were quite low (geometric mean: 0.01 μg/m3; 95 % CI: 0.01–0.02 μg/m3) and were all below the limit of quantification in control homes. Seven-day concentrations of PM2.5 and PM1.0 in e-cigarette and control homes were similar. Airborne nicotine and PM concentrations did not differ according to different e-cigarette use characteristics. Non-users residing with e-cigarette users had low but significantly higher levels of cotinine, 3′-OH-cotinine and 1,2-propanediol in saliva, and cobalt in urine than non-users living in control homes. In conclusion, e-cigarette use at home created bystanders' exposure to SHA regardless of the e-cigarette use characteristics. Further studies are warranted to assess the implications of SHA exposure for smoke-free policy.

Effect of e-cigarette refill liquid on follicular development and estrogen secretion in rats.

INTRODUCTIONElectronic cigarettes (e-cigarettes) have recently become popular as an alternative to conventional cigarettes. The aim of this study is to investigate the effects of e-cigarette refill liquid (e-liquid) on follicular development and estrogen secretion in rats and whether it is related to the Hippo signaling pathway, a pathway that can regulate follicle growth.METHODSOvaries from 21- and 35-day-old rats were divided into three groups: control (no intervention), 0.05 mg, and 0.5 mg (e-liquids containing 0.5 mg and 5 mg of nicotine/kg). The rates were cultured for three hours in vitro. At the end of culture, HE staining was performed to observe the follicle morphology and calculate the percentage of normal follicles, and the expression of Yes-associated protein (YAP, target factors of the Hippo signaling pathway) and CYP19 (aromatase, a key enzyme in estrogen synthesis) were observed by immunohistochemistry. Western blotting was performed to detect the expression levels of CYP19, YAP, phosphorylated YAP (PYAP), large tumor suppressor 2 (LATS2, factors upstream of YAP in the Hippo signaling pathway), and phosphorylated LATS2 (PLATS2). Estrogen concentrations were determined using ELISA.RESULTSHE staining showed that the percentage of normal follicles decreased, and immunohistochemistry showed that the expression of CYP19 and YAP significantly decreased after e-liquid intervention. ELISA showed that the estrogen concentration in the ovaries decreased after e-liquid intervention. Western blot results indicated that CYP19, LATS2, and YAP expression, decreased after e-liquid intervention, but PLATS2 and PYAP expression increased.CONCLUSIONSWe found that the e-liquids may impair the development of rat ovarian follicles and reduce estrogen secretion through Hippo signaling pathway.

Effects of E-Cigarette Refill Liquid Flavorings with and without Nicotine on Human Retinal Pigment Epithelial Cells: A Preliminary Study.

Smoking is an etiologic factor for age-related macular degeneration (AMD). Although cigarette smoke has been extensively researched for retinal pigment epithelial (RPE) cell degeneration, the potential for adverse effects on the retinal epithelium following exposure to flavored e-cigarette refill liquid has never been explored. In this preliminary study, we have examined the effects of 20 e-liquids (10 different flavored nicotine-free and 10 nicotine-rich e-liquids) used in e-cigarettes on the metabolic activity, membrane integrity, and mitochondrial membrane potential of RPE cells. Our results showed that of the flavors studied over the concentration range: 0.5, 1, and 2% v/v for a duration of 48 h, cinnamon was the most toxic and menthol was the second most toxic, while other flavors showed lesser or no cytotoxicity. The presence of nicotine augmented cytotoxicity for cinnamon, menthol, strawberry, vanilla, and banana while for other flavors there was no synergism. Together, our results demonstrate that exposure of RPE to flavored e-cigarette refill liquids caused significant cytotoxicity and may be a risk factor for the development of retinal pathogenesis, although further in-depth studies are necessary.

Development of a “Freeze-Pour” Sample Preparation Method for the GC Analysis of Semivolatile Flavouring Chemicals Present in E-cigarette Refill Liquids

During the past decade, e-cigarettes have become increasingly popular. To guarantee their safe use and to comply with the notification requirements of the EU Tobacco Product Directive, the EU member state regulatory authorities need information about the exact composition of the e-liquids and their emissions. However, one of the challenges encountered during the analysis of e-liquids is the presence of the highly abundant e-liquid matrix components propylene glycol and glycerol. In this study, headspace gas chromatography (HS-GC) analysis is presented as an excellent method for the analysis of high volatile components in e-liquids. For the analysis of semivolatile ingredients, an additional sample preparation step is proposed based on a liquid–liquid extraction (LLE) followed by a freeze-out of the matrix components. The developed method was successfully validated in accordance with the validation requirements of ICH guidelines for the quantification of four flavourings with a potential health concern for e-cigarette users.

E-cigarette, or Vaping, Associated Lung and Hepatic Injury.

E-cigarette, or Vaping, Associated Lung and Hepatic Injury.

Compliance of e-cigarette refill liquids with regulations on labelling, packaging and technical design characteristics in nine European member states

ObjectiveTo evaluate electronic cigarette (e-cigarette) product compliance with European regulations (Tobacco Products Directive (TPD), Implementing Decisions), with a focus on labelling/packaging practices and technical design/safety features.MethodsBefore the implementation of the...

Corrigendum to: Impact of the Revised European Tobacco Product Directive on the Quality of E-cigarette Refill Liquids in Belgium.

Corrigendum to: Impact of the Revised European Tobacco Product Directive on the Quality of E-cigarette Refill Liquids in Belgium.

Impact of the Revised European Tobacco Product Directive on the Quality of E-cigarette Refill Liquids in Belgium.

Since its introduction, the e-cigarette has become a commonly used consumer product. In this study, we investigate whether regulatory changes had an impact on the quality of refill liquids (e-liquids) available on the Belgian market through analysis of their chemical composition. Hence, the nicotine concentration accuracy was investigated in samples before, during and after the implementation of the revised Tobacco Product Directive (TPD) as an indicator of good manufacturing practices. This is, however, not enough to assure the quality. Therefore, extra criteria were also assessed based on TPD requirements. By using in-house validated methods, a total of 246 e-liquids purchased prior (2013-2015), during (2016) and after (2017-2018) the implementation of the TPD revisions, were analyzed for the presence of nicotine, nicotine-related impurities, volatile organic compounds (VOCs), caffeine and taurine, and the flavors diacetyl and acetylpropionyl. Although not all manufacturers managed to produce and label their products accurately, nicotine labeling discrepancies have decreased over time. Moreover, also the number of e-liquids, containing high-risk VOCs (10% in 2016 vs. none of the samples in 2017-2018), caffeine (16% in 2017 vs. 5% in 2018), and diacetyl and acetylpropionyl (50% in 2017 vs. 27% in 2018 of sweet-flavored samples) diminished over time. Our results demonstrate that the overall quality of the e-liquids has improved after the implementation of the revised TPD. However, the results also show that periodic quality control might be required to ensure further compliance to the TPD. This study clearly demonstrates that the implementation of the revised TPD has improved the quality of the e-liquids on the Belgian market. However, there are still e-liquids that are not in agreement with the TPD due to nicotine concentration label discrepancies, presence of e-liquid impurities and controversial flavors diacetyl and acetylpropionyl or the additive caffeine.

A STUDY TO DETECT THE SAFETY OF ELECTRONIC CIGARETTE ON THE TASTE BUDS OF ALBINO RATS TONGUE PAPILLAE

Background: Electronic cigarette is a substitute to traditional nicotine smoke invented since 2004. There is no enough data about its safety with its the widespread usage.Aim of the study: The present study was designed to verify the impact of E-liquid of electronic cigarette on taste buds of fungiform papillae in albino rats.Materials and methods: 22 young adult male albino rats were divided into 3 groups. Group I: (control group), injected i.p by normal saline daily. Group II: (E-cigarette group): animals were injected i.p by E-cigarette refill liquid (ECRL) containing 0.5 mg of nicotine/kg for 6 days then continue to be administered the same dose day after day for 4 weeks. Group III (E-cigarette + vitamin C treated group): animals had been i.p injected by (ECRL) containing 0.5 mg of nicotine/kg. One hour from i.p injection of the liquid, the animals were received vitamin C 300 mg/ kg through oro-gastric gavage for 6 days. Then animals were receive the regimen day after day till the end of 4 weeks. Rats of groups sacrificed 24 hs from last injection. After processing the tissue samples, they were stained using Haematoxylin & Eosin and Cytokeratin 7 & TNF α. The results were analyzed statistically using one way ANOVA test.Results: Evaluation of the sections revealed significant differences between all groups with marked improvement in group III. p value was less than 0.05.Conclusion: E-cigarette smoking has a harmful effect on taste buds of fungiform papilla histologically and immunohistochemically. Vitamin C has a protective effect on taste bud against E-cigarette refill liquid.

Flavors, additives and nicotine levels detected among the most popular e-cigarette refill liquids across 9 European countries after the implementation of Tobacco Products Directive (TPD)

Flavors, additives and nicotine levels detected among the most popular e-cigarette refill liquids across 9 European countries after the implementation of Tobacco Products Directive (TPD)

A simple dilute-and-shoot method for screening and simultaneous quantification of nicotine and alkaloid impurities in electronic cigarette refills (e-liquids) by UHPLC-DAD

The electronic cigarette (e-cigarette) has emerged as a popular alternative to the traditional hazardous tobacco cigarette. The substantial increase in e-cigarette use also urgently calls for controlling the quality of e-cigarette refill liquid products (e-liquids). Currently, the most important quality indicator of e-liquid products is the quantification of nicotine and its related impurities. Although different methods have been published to measure nicotine and impurity levels, the majority of them use a targeted LC-MS/MS approach. There is, however, a need for more robust quantification methods that are easy to implement in most control (industrial and governmental) laboratories. Therefore, in this study, a simple dilute-and-shoot UHPLC-DAD method has been developed and validated for the simultaneous quantification of nicotine and its alkaloid impurities in electronic cigarette refills. An optimal separation of the alkaloids was achieved in a runtime of 11 min. The method was successfully validated using the “total error” approach in accordance with the validation requirements of ISO-17025. During this validation, interference between the target components and a number of popular flavouring compounds such as vanillin, maltol, ethylacetate, etc. could be excluded. In addition, small changes to the column temperature, pH and molar concentration of the mobile phase buffer were deliberately introduced in order to assess the robustness of the method. Only a slightly different outcome between the newly developed UV-detection method and the targeted MS approach was found, due to the sensitivity of the different detection techniques. However, in the context of quality control of nicotine related impurities, for which the European Pharmacopoeia limits are currently applied, the sensitivity of the UHPLC-DAD method was found to be within the acceptable range. Despite the somewhat lower selectivity of the newly developed UV-detection technique versus a targeted LC-MS/MS approach, it may be concluded that this method is a suitable alternative for quality control purposes.

Electronic cigarette usage patterns: a case study combining survey and social media data.

To identify who were social media active e-cigarette users, to compare the use patterns from both survey and social media data for data triangulation, and to jointly use both datasets to conduct a comprehensive analysis on e-cigarette future use intentions. We jointly used an e-cigarette use online survey (n = 5132) and a social media dataset. We conducted analysis from 3 different perspectives. We analyzed online forum participation patterns using survey data. We compared e-cigarette use patterns, including brand and flavor types, ratings, and purchase approaches, between the 2 datasets. We used logistic regression to study intentions to use e-cigarettes using both datasets. Male and younger e-cigarette users were the most likely to participate in e-cigarette-related discussion forums. Forum active survey participants were hardcore vapers. The e-cigarette use patterns were similar in the online survey data and the social media data. Intention to use e-cigarettes was positively related to e-liquid ratings and flavor ratings. Social media provided a valuable source of information on users' ratings of e-cigarette refill liquids. For hardcore vapers, social media data were consistent with online survey data, which suggests that social media may be useful to study e-cigarette use behaviors and can serve as a useful complement to online survey research. We proposed an innovative framework for social media data triangulation in public health studies. We illustrated how social media data, combined with online survey data, can serve as a new and rich information source for public health research.

Classification, labelling and packaging of the most popular e-cigarette refill liquids across 9 European countries

Classification, labelling and packaging of the most popular e-cigarette refill liquids across 9 European countries

Effects of nicotine-containing and “nicotine-free” e-cigarette refill liquids on intracranial self-stimulation in rats

BackgroundAnimal models are needed to inform FDA regulation of electronic cigarettes (ECs) because they avoid limitations associated with human studies. We previously reported that an EC refill liquid produced less aversive/anhedonic effects at a high nicotine dose than nicotine alone as measured by elevations in intracranial self-stimulation (ICSS) thresholds, which may reflect the presence of behaviorally active non-nicotine constituents (e.g., propylene glycol) in the EC liquids. The primary objective of this study was to assess the generality of our prior ICSS findings to two additional EC liquids. We also compared effects of “nicotine-free” varieties of these EC liquids on ICSS, as well as binding affinity and/or functional activity of nicotine alone, nicotine-containing EC liquids, and “nicotine-free” EC liquids at nicotinic acetylcholine receptors (nAChRs). Methods and resultsNicotine alone and nicotine dose-equivalent concentrations of both nicotine-containing EC liquids produced similar lowering of ICSS thresholds at low to moderate nicotine doses, indicating similar reinforcement-enhancing effects. At high nicotine doses, nicotine alone elevated ICSS thresholds (a measure of anhedonia-like behavior) while the EC liquids did not. Nicotine-containing EC liquids did not differ from nicotine alone in terms of binding affinity or functional activity at nAChRs. “Nicotine-free” EC liquids did not affect ICSS, but bound with low affinity at some (e.g., α4ß2) nAChRs. ConclusionsThese findings suggest that non-nicotine constituents in these EC liquids do not contribute to their reinforcement-enhancing effects. However, they may attenuate nicotine’s acute aversive/anhedonic and/or toxic effects, which may moderate the abuse liability and/or toxicity of ECs.

Effects of isolated tobacco alkaloids and tobacco products on deprivation-induced food intake and meal patterns in rats

The ability of smoking to reduce body weight serves as motivation for continued smoking. It is unclear to what extent non-nicotine constituents in cigarettes are contributing to the weight-reducing effect of smoking. The purpose of the current study was to examine the effects of nicotine and four minor tobacco alkaloids (nornicotine, cotinine, anatabine, and anabasine) on food intake, one of the key regulators of body weight. In addition, a smokeless tobacco extract (STE) and e-cigarette (EC) refill liquid were used to model the effects of actual tobacco product exposure on food intake. Male Holztman rats were trained to lever press for food pellets during daily 2h sessions in operant chambers. In Experiment 1, the effects of subcutaneous injections of saline, nicotine (0.25–1.00mg/kg), nornicotine (0.50–6.00mg/kg), cotinine (1.00–100.00mg/kg), anatabine (0.25–3.00mg/kg), and anabasine (0.50–4.00mg/kg) were assessed. In Experiment 2, rats from Experiment 1 were used to examine the effects of nicotine, STE, and EC liquid. All alkaloids, except cotinine, produced a dose-dependent reduction in overall food intake. The highest doses of all drugs significantly reduced latency and response rate to obtain the first pellet. At some doses, nicotine, anatabine, and nornicotine reduced food intake within the first 45min without compensatory increases in intake later in the session. STE and EC liquid produced dose dependent decreases in food intake similar to nicotine alone. These data suggest that minor tobacco alkaloids have appetite suppressant effects and warrant further investigation into their effects on body weight, energy intake, and energy expenditure under free-feeding conditions. However, findings with STE and EC liquid suggest that nicotine is the primary constituent in these products to affect food intake, whereas levels of minor alkaloids in these products may be too low to influence food intake.

Flavors and additives detected among the most popular e-cigarette refill liquids across 9 European countries

Flavors and additives detected among the most popular e-cigarette refill liquids across 9 European countries

Differences in reported vs. Measured Nicotine Concentrations among the most popular e-cigarette refill liquids across 9 European Countries

Differences in reported vs. Measured Nicotine Concentrations among the most popular e-cigarette refill liquids across 9 European Countries