McAdam Kevin, Waters Gareth, Moldoveanu Serban, Margham Jennifer, Cunningham Anthony, Vas Carl, Porter Andrew, Digard Helena
McAdam Scientific Ltd., Eastleigh, United Kingdom.
Research and Development, British American Tobacco, Southampton, United Kingdom.
Front Chem. 2021 Sep 23;9:742538. doi: 10.3389/fchem.2021.742538. eCollection 2021.
Concerns over the presence of the diketones 2,4 butanedione (DA) and 2,3 pentanedione (AP) in e-cigarettes arise from their potential to cause respiratory diseases. Their presence in e-liquids is a primary source, but they may potentially be generated by glycerol (VG) and propylene glycol (PG) when heated to produce aerosols. Factors leading to the presence of AP, DA and acetoin (AC) in e-cigarette aerosols were investigated. We quantified direct transfer from e-liquids, examined thermal degradation of major e-liquid constituents VG, PG and 1,3 propanediol (1,3 PD) and the potential for AC, AP and DA production from sugars and flavor additives when heated in e-cigarettes. Transfers of AC, AP and DA from e-liquids to e-cigarette aerosols were quantified by comparing aerosol concentrations to e-liquid concentrations. Thermal generation from VG, PG or 1,3 PD e-liquids was investigated by measuring AC, AP and DA emissions as a function of temperature in an e-cigarette. Thermal generation of AC, AP and DA from sugars was examined by aerosolising e-liquids containing sucrose, fructose or glucose in an e-cigarette. Pyrolytic formation of AP and DA from a range of common flavors was assessed using flash pyrolysis techniques. AC transfer efficiency was >90%, while AP and DA were transferred less efficiently (65%) indicating losses during aerosolisation. Quantifiable levels of DA were generated from VG and PG, and to a lesser extent 1,3 PD at coil temperatures >300°C. Above 350°C AP was generated from VG and 1,3 PD but not PG. AC was not generated from major constituents, although low levels were generated by thermal reduction of DA. Aerosols from e-liquids containing sucrose contained quantifiable (>6 ng/puff) levels of DA at all sucrose concentrations tested, with DA emissions increasing with increasing device power and concentration. 1% glucose, fructose or sucrose e-liquids gave comparable DA emissions. Furanose ring compounds also generate DA and AP when heated to 250°C. In addition to less than quantitative direct transfer from the e-liquid, DA and AP can be present in the e-cigarette aerosol due to thermal decomposition reactions of glycols, sugars and furanonse ring flavors under e-cigarette operating conditions.
电子烟中存在二酮类物质2,4 - 丁二酮（DA）和2,3 - 戊二酮（AP）引发了人们的担忧，因为它们有可能导致呼吸系统疾病。它们在电子烟液中的存在是一个主要来源，但在加热产生气溶胶时，甘油（VG）和丙二醇（PG）也可能产生这些物质。研究了导致电子烟气溶胶中存在AP、DA和乙偶姻（AC）的因素。我们对电子烟液的直接转移进行了量化，研究了电子烟液主要成分VG、PG和1,3 - 丙二醇（1,3 - PD）的热降解情况，以及电子烟中加热时糖和香料添加剂产生AC、AP和DA的可能性。通过比较气溶胶浓度和电子烟液浓度，对AC、AP和DA从电子烟液到电子烟气溶胶的转移进行了量化。通过测量电子烟中AC、AP和DA的排放随温度的变化，研究了VG、PG或1,3 - PD电子烟液的热生成情况。通过雾化电子烟中含有蔗糖、果糖或葡萄糖的电子烟液，研究了糖产生AC、AP和DA的热生成情况。使用快速热解技术评估了一系列常见香料热解形成AP和DA的情况。AC的转移效率>90%，而AP和DA的转移效率较低（65%），表明在雾化过程中有损失。在线圈温度>300°C时，VG和PG会产生可量化水平的DA，1,3 - PD产生的量较少。在350°C以上，VG和1,3 - PD会产生AP，但PG不会。主要成分不会产生AC，不过DA的热还原会产生少量AC。在所有测试的蔗糖浓度下，含有蔗糖的电子烟液产生的气溶胶中DA含量均可量化（>6纳克/口），DA排放量随设备功率和浓度的增加而增加。1%的葡萄糖、果糖或蔗糖电子烟液产生的DA排放量相当。呋喃糖环化合物在加热到250°C时也会产生DA和AP。除了电子烟液的直接转移不完全定量外，在电子烟工作条件下，二醇、糖和呋喃糖环香料的热分解反应也会使DA和AP存在于电子烟气溶胶中。
