The Use of HPLC-PDA in Determining Nicotine and Nicotine-Related Alkaloids from E-Liquids: A Comparison of Five E-Liquid Brands Purchased Locally

Emerging trends in functional materials for electrochemical sensors in nicotine determination

In the past year, there has been significant progress in the utilization of electrochemical strategies for the determination of harmful substances. Among those, the electrochemical determination of nicotine (NIC) has continued to be of significant interest ascribed to the global health concern of e-cigarette products, nowadays. Electrochemical sensors have become promising tools for the detection of NIC ascribed to their high sensitivity, selectivity, and ease of use. This review article provides a concise overview of the advanced developments in electrochemical sensors for NIC detection using modified functional materials such as carbon-based materials, metal-organic frameworks (MOF), MXene, polymer, and metallic based modifiers. The sensitivity of electrochemical sensors can be improved by modifying them with these conductive materials ascribed to their physical and chemical properties. The review also addresses the challenges and future perspectives in the field, including sensitivity and selectivity improvements, stability and reproducibility issues, integration with data analysis techniques, and emerging trends. In conclusion, this review article may be of interest to researchers intending to delve into the development of functional electrochemical sensors in future studies.

Recent advances in the analysis of electronic cigarette liquids and aerosols: Sample preparation and chromatographic characterization

Electronic cigarette (e-cigarette) usage has risen dramatically worldwide in recent years. It has been publicized as a safer alternative to the conventional combustible cigarette. This, however, has not yet been supported by robust toxicological research evidence. Analysis of the chemical compositions of e-liquids and generated aerosols is an important step in evaluating the toxicity effects of e-cigarettes. Currently, a broad spectrum of analytical methods have been employed for qualitative and quantitative analysis of chemical compositions of e-cigarette liquids and aerosols. The aim of this article is to review the advances in the chromatographic characterization of chemical composition of the latter in the recent five years. In addition, sample preparation methods for e-liquids and aerosols are surveyed and discussed. A study of the relevant literature indicates that, expectedly, gas chromatography and liquid chromatography with a variety of detection systems, particularly mass spectrometry, have been the main analytical techniques used in this field. Sample preparation procedures primarily include headspace sampling, dilute-and-shoot approach, liquid-liquid extraction and sorbent-based extraction for e-liquids and for aerosols (the latter usually with laboratory-built collection devices). Some challenges of current e-cigarette analytical research, and an overview on prospective work are also presented.

Electronic nicotine delivery systems (ENDS): A convenient means of smoking?

Electronic nicotine delivery systems (ENDS), which are becoming increasingly popular in many parts of the world, have recently become more sophisticated in terms of their more active content and better controlled vaporisation. This review begins by describing how cigarette smoking led to the development of ENDS as a means of combatting nicotine addiction. ENDS are usually categorised as belonging to one of only three main generations, but a fourth has been added in order to differentiate the latest, most powerful, most advanced and innovative that have improved heating efficiency. Descriptions of the principal substances contained in ENDS are followed by considerations concerning the risk of toxicity due to the presence of albeit low concentrations of such a variety of compounds inhaled over a long time, and the increasingly widespread use of ENDS as a means of smoking illicit drugs. We also review the most widely used pharmacotherapeutic approaches to smoking cessation, and recent epidemiological data showing that ENDS can help some people to stop smoking. However, in order to ensure their appropriate regulation, there is a need for higher-quality evidence concerning the health effects and safety of ENDS, and their effectiveness in discouraging tobacco smoking.

Minor Tobacco Alkaloids as Biomarkers to Distinguish Combusted Tobacco Use From Electronic Nicotine Delivery Systems Use. Two New Analytical Methods

Biomarkers for the use of electronic nicotine delivery systems (ENDS) are desirable for studies of the health effects of electronic cigarettes and related devices. However, the aerosols inhaled from these devices do not contain substances that are unique to this class of products, i.e., substances that are not present in cigarette smoke or those that do not have common environmental or dietary sources. Consequently, identifying selective biomarkers for ENDS use remains a challenge. If co-use of conventional tobacco products can be definitively ruled out, then nicotine and its metabolites are suitable for assessing exposure. Self-reports from questionnaires are often used to obtain information on product use. But self-reports may not always be accurate, and are not amenable to obtaining quantitative information on exposure. An alternative approach is to use selective biomarkers for conventional tobacco products to definitively rule out their use. In this article, we describe two new LC-MS/MS methods for the minor tobacco alkaloids anabasine, anatabine, nicotelline, anatalline, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a tobacco-specific nitrosamine metabolite, all biomarkers that are selective for the use of conventional tobacco products. Applications of these biomarkers in studies of ENDS use and dual use of ENDS and conventional tobacco products are also discussed.

Mechanistic Effects of E-Liquids on Biofilm Formation and Growth of Oral Commensal Streptococcal Communities: Effect of Flavoring Agents

Background: Vaping has become a global health concern. As research continues, more studies are beginning to question the relative safety of E-liquid flavoring additives. The oral cavity is the first site of exposure to E-liquid aerosol, making it critical for investigation. Because of the importance of commensal bacterial biofilms for oral health, we sought to explore the effects of E-liquids ± flavors on the formation and growth of single- and multi-species biofilms and to investigate the mechanism of inhibition. Methods: Quantitative and confocal biofilm analysis, death curves, and colony-forming units (CFU) were evaluated with flavorless and flavored (tobacco, menthol, cinnamon, strawberry, blueberry) E-liquids using four strains of oral commensal bacteria (Streptococcus gordonii, Streptococcus intermedius, Streptococcus mitis, and Streptococcus oralis). Results: All flavoring agents show a dose-dependent inhibition in the growth of single-species and multi-species biofilms. Furthermore, CFUs, death curves, and light microscopy show that flavoring agents have a bactericidal mode of inhibition on the growth of these oral streptococci. Conclusions: These results show that flavored, rather than unflavored, E-liquids are more detrimental to biofilm formation and growth of oral commensal bacteria. Consequently, E-liquid flavorings agents could pose risks to the oral microenvironment, and by extension, to systemic health.

Fabrication and Validation of an Economical, Programmable, Dual-Channel, Electronic Cigarette Aerosol Generator

Vaping (inhalation of electronic cigarette-generated aerosol) is a public health concern. Due to recent spikes in adolescent use of electronic cigarettes (ECIGs) and vaping-induced illnesses, demand for scientific inquiry into the physiological effects of electronic cigarette (ECIG) aerosol has increased. For such studies, standardized and consistent aerosol production is required. Many labs generate aerosol by manually activating peristaltic pumps and ECIG devices simultaneously in a predefined manner. The tedium involved with this process (large puff number over time) and risk of error in keeping with puff topography (puff number, duration, interval) are less than optimal. Furthermore, excess puffing on an ECIG device results in battery depletion, reducing aerosol production, and ultimately, its chemical and physical nature. While commercial vaping machines are available, the cost of these machines is prohibitive to many labs. For these reasons, an economical and programmable ECIG aerosol generator, capable of generating aerosol from two atomizers simultaneously, was fabricated, and subsequently validated. Validation determinants include measurements of atomizer temperatures (inside and outside), electrical parameters (current, resistance and power) of the circuitry, aerosol particle distribution (particle counts and mass concentrations) and aerosol delivery (indexed by nicotine recovery), all during stressed conditions of four puffs/minute for 75 min (i.e., 300 puffs). Validation results indicate that the ECIG aerosol generator is better suited for experiments involving ≤100 puffs. Over 100 puffs, the amount of variation in the parameters measured tends to increase. Variations between channels are generally higher than variations within a channel. Despite significant variations in temperatures, electrical parameters, and aerosol particle distributions, both within and between channels, aerosol delivery remains remarkably stable for up to 300 puffs, yielding over 25% nicotine recovery for both channels. In conclusion, this programmable, dual-channel ECIG aerosol generator is not only affordable, but also allows the user to control puff topography and eliminate battery drain of ECIG devices. Consequently, this aerosol generator is valid, reliable, economical, capable of using a variety of E-liquids and amenable for use in a vast number of studies investigating the effects of ECIG-generated aerosol while utilizing a multitude of puffing regimens in a standardized manner.

A systematic review of refillable e-liquid nicotine content accuracy

OBJECTIVES

The use of e-cigarettes is becoming more common in the United States. E-cigarettes are often refilled with nicotine-containing solutions of various concentrations purchased in local shops or on the Internet. There is evidence that the nicotine content in these solutions is often mislabeled; thus, we reviewed the available literature on this topic.

DATA SOURCES

We conducted a systematic review of peer-reviewed articles published worldwide on e-liquid nicotine content accuracy using the databases CAB Direct, Cochrane Central Register of Controlled Trials, PubMed, and SPORTDiscus (EBSCO).

STUDY SELECTION

Initial screening of titles and abstracts was conducted to determine relevancy for inclusion. Full-article reviews of studies involving the purchase and chemical analysis of nicotine content in refillable e-liquids were conducted for final inclusion.

DATA EXTRACTION

Data extraction included e-liquid sample size, whether the samples were labeled to contain nicotine, whether the samples were purchased in retail shops or online, and the number and percentage of samples where the analyzed nicotine content fell outside 10% of the labeled nicotine content.

RESULTS

Twenty articles described cross-sectional studies of purchased samples containing nicotine. The number of nicotine-containing e-liquid samples obtained in each study varied from 2 to 71. The percentage of samples with an analyzed nicotine concentration of more than 10% above or below the labeled nicotine concentration ranged from 0% to 100% (277/574 or 48.3%; median 46.85%). A large percentage of the samples deviated by 10% from the labeled nicotine concentrations in both U.S. and non-U.S. samples, with U.S. samples having a higher percentage.

CONCLUSION

Our review shows that actual nicotine concentrations in e-liquids may vary considerably from labeled concentrations. Pharmacists should warn patients to be wary of the contents of e-cigarettes, and explain the dangers of using these products.

A Comparison of Flavorless Electronic Cigarette-Generated Aerosol and Conventional Cigarette Smoke on the Planktonic Growth of Common Oral Commensal Streptococci

Background: Smoking is the number one predictor for the development of periodontal disease. Consequently, electronic cigarette (ECIG) use has prompted investigations into the health-related risks induced by ECIG-generated aerosol on oral commensal bacteria as compared to cigarette smoke. Since E-liquid contains fewer constituents than smoke, we hypothesize that growth media containing E-liquid or aerosol has less impact on oral commensal streptococci than cigarette smoke. Methods: Eight-hour growth curves were generated for three strains of streptococci following exposure of growth media to nicotine alone (0.05, 0.1, 0.2 mg/mL), E-liquid ± nicotine (2.3, 4.7, 7.0 µL/mL), ECIG-generated aerosol ± nicotine (25, 50, 75 puffs), or cigarette smoke (2, 5, 10, 25, 50, 75 puffs). Nicotine and E-liquid were added to the media at concentrations equivalent to vaporized amounts of 25, 50, or 75 puffs. Absorbance readings were taken at 0, 2, 4, 6, and 8 h of bacterial growth. Results: Both E-liquid and aerosol (±nicotine) had little to no effect on eight-hour streptococcal growth. In contrast, five puffs of smoke inhibited streptococcal growth. Conclusions: Smoke-treated growth media, but not E-liquid or ECIG-generated aerosol, inhibits the growth of oral commensal streptococci. A possible implication is that aerosol may induce less periodontitis than smoke.