Liquid Chromatographic Analysis of Carbonyl Compounds in Aerosols from High and Low Nicotine E-Cigarette Liquids Mirroring Realistic Puffing Topography Kimber CF1, Kośmider L2, Kurek J2, Corcoran O3, Dawkins LE4 c.kimber@uel.ac.uk leon.kosmider@gmail.com 1) Drugs and Addictive Behaviours Research Group, School of Psychology, University of East London, Water lane, Stratford, London, E15 4LZ, UK ; 2) Institute of Occupational Medicine and Environmental Health, Poland; 3) The Medicines Research Group, School of Health, Sport and Bioscience, University of East London, Stratford campus; 4) Division of Psychology, School of Applied Sciences, 103 Borough Road, London South Bank University, London, SE1 0AA, UK Introduction Results Tobacco smokers engage in more intensive puffing regimes (more frequent and longer puffs) when switching from higher to lower nicotine-containing cigarettes [1,2,3,4], this can result in increased toxicant exposure [5]. Such compensatory puffing behaviour has recently been demonstrated in experienced vapers using high and low nicotine concentration liquids in the lab [6]. Although exposure to toxins in e-cigarette aerosols is negligible by comparison with tobacco smoke [7], whether a more intensive puffing regime associated with using a lower nicotine concentration liquid increases exposure, has not been explored. This research is particularly timely with the recent introduction (20th May 2016) of the European Tobacco Product Directive (EU-TPD). In the liquid, there was no statistical difference between conditions for levels of acetaldehyde (p = 0.41). Levels of formaldehyde, acetone and acrolein were either not detected (N.D) or below the limit of quantification (BLQ). In the aerosols, based on participants’ puffing topography, levels detected were as follows for: formaldehyde 3.41 ±0.94 vs 1.49 ±0.30, acetaldehyde 2.17 ±0.36 vs 1.04 ±0.13 and acetone 0.73 ±0.20 vs 0.28 ±0.14 (all p < 0.01) in the 6 and 24 mg/mL nicotine concentration liquids respectively. Acrolein was not detected (figure 3). Table 2. Levels of carbonyl compounds found in liquids Levels (µg/50µl) in Liquids Formaldehyde Acetaldehyde Acetone Acrolein 6 mg/mL N.D 0.059 – 0.075 BLQ 24 mg/mL 0.043 – 0.067 0.080 – 0.094 Aims To establish whether more intensive puffing regimes associated with using a lower nicotine concentration produces higher levels of toxicants from e-cigarette nicotine aerosols. Table 3. Levels of carbonyl compounds found in aerosols Levels (µg) in Aerosols Formaldehyde Acetaldehyde Acetone Acrolein 6 mg/mL 3.058 - 4.966 2.119 - 2.736 0.434 - 0.979 N.D 24 mg/mL 0.950 - 1.770 0.831 - 1.143 0.158 - 0.553 Methodology HPLC/diode array analysis was employed. Four carbonyl compounds formaldehyde, acetaldehyde, acrolein and acetone were quantified in liquid (vehicle of propylene glycol and vegetable glycerine 50/50%) and aerosol using 24 mg/mL and 6 mg/mL nicotine concentration liquids. Aerosols were generated by a smoking machine (figure 2; University of Technology, Lodz, Poland [8]) configured to exactly replicate puffing topography data obtained from a sample of 12 experienced vapers using both aforementioned solutions, for 1 h [6]. The ‘Joyetech eVic Supreme’ e-cigarette (figure 1) (output voltage 3.9) was mounted with the Aspire Nautilus BVC tank (atomiser 1.8 Ohm). The 6 mg/mL liquid was used more intensively compared to the 24 mg/mL. Results are presented in number of puffs taken on average for 1 h of e-cigarette use (74 and 47 for 6 and 24 mg/mL liquids respectively as per the puffing topography in Dawkins et al, in press; table 1). Analyses was performed 6 times for each solution. T-tests were used for comparing the means in aerosols and in solutions. Figure 2. Smoking machine Figure 3. Levels of toxicants detected in aerosols Table 1. Puffing protocol used in the study * P < 0.01; whiskers - SEM Puff duration Number of puffs Intervals between puffs Sampling time 24 mg/mL 3.76s. 14 74.5s. 1017s. 6 mg/mL 5.04s. 44.3s. 641s. Conclusions The smoking machine, programmed with a more intensive puffing regimen to reflect compensation by experienced vapers on lower nicotine concentration liquid, resulted in higher aerosol levels of formaldehyde, acetaldehyde and acetone. Our findings suggest, vapers making a sudden switch to much lower nicotine concentration liquid (either due to the EU-TPD implementation or personal choice) may inadvertently increase their exposure to carbonyl compounds through compensatory puffing behaviour. Figure 1. E-cigarette and tank used in the study References Ashton H, Stepney R, Thompson JW. Self-titration by cigarette smokers. Br Med J. 1979 Aug 11;2(6186):357-60. Hasenfratz M, Baldinger B, Bättig K. Nicotine or tar titration in cigarette smoking behavior?. Psychopharmacology. 1993 Sep 1;112(2-3):253-8. Herning RI, Jones RT, Bachman J, Mines AH. Puff volume increases when low-nicotine cigarettes are smoked. Br Med J (Clin Res Ed). 1981 Jul 18;283(6285):187-9. Russell MA, Jarvis M, Iyer R, Feyerabend C. Relation of nicotine yield of cigarettes to blood nicotine concentrations in smokers. Br Med J. 1980 Apr 5;280(6219):972-6. Strasser AA, Lerman C, Sanborn PM, Pickworth WB, Feldman EA. New lower nicotine cigarettes can produce compensatory smoking and increased carbon monoxide exposure. Drug and alcohol dependence. 2007 Jan 12;86(2):294-300.. Dawkins, L., Kimber, C., Doig, M., Feyerabend., C., Corcoran, O. (in press) Self-Titration by Experienced E-cigarette Users: Blood Nicotine Delivery and Subjective Effects. Psychopharmacology. Goniewicz ML, Knysak J, Gawron M, Kosmider L, Sobczak A, Kurek J, Prokopowicz A, Jablonska-Czapla M, Rosik-Dulewska C, Havel C, Jacob P. Levels of selected carcinogens and toxicants in vapour from electronic cigarettes. Tobacco control. 2014 Mar 1;23(2):133-9. Goniewicz ML, Kuma T, Gawron M, Knysak J, Kosmider L. Nicotine levels in electronic cigarettes. Nicotine & Tobacco Research. 2012 Apr 22:nts103. Competing interests No financial support from any companies was received for this work and there are no non-financial conflicts of interest that would be considered relevant to this work. CFK, LK and JK declare no competing interests. LED and OC have previously conducted research for several independent electronic cigarette companies. These companies had no input into the design, conduct or write up of the projects. LED has also acted as a consultant for the pharmaceutical industry and as an expert witness in a patent infringement case. www.uel.ac.uk/psychology