Measuring volatile nicotine from electronic cigarettes

Abstract

This thesis is focused on electronic cigarettes and the formulations (also known as e-juices) associated with these. The reason is that there have been countless studies on the health effects and nicotine delivery of normal cigarettes, but not as much on electronic cigarettes. This work aims to provide some insights into how electronic cigarettes behaves as nicotine delivery system. The overall research question is how different compositions of e-juice affects the release of nicotine vapor from the produced aerosol particles. Depending on if the nicotine is in gas phase or aerosol particle phase effects how the deposition and uptake occurs in the body. This is interesting to be able to compare nicotine delivery of electronic cigarettes to normal cigarettes, as well as understand the effect of e-cigarettes better.

This thesis looked at how e-juice with propylene glycol compares to the use of glycerol, but also how addition of water changes the results. Along the way, different parameters were studied to see how, or if, the nicotine evaporation changed as well as size distribution for the aerosol particles formed.

A denuder with oxalic acid coating was used to catch the nicotine vapor leaving the aerosol particle as well as oxalic coated filters at the end. The purpose of the filters was to capture all the aerosol particles. For the size measurements, a scanning mobility particle sizer (SMPS) as well as a next generation impactor (NGI) was used to study how the different formulations affected the size distribution. An aerosol mass spectrometer (AMS) was also used to see how the chemical composition of the aerosol particles changed over time.

The key result was that glycerol in the e-juice increases the vapor release between 2-4 times compared to propylene glycol. It was observed that for propylene glycol the addition of water did not affect the release significantly, while for glycerol a larger change could be seen. The size of the aerosol particles was similar regardless of formulation.

The conclusion drawn from this is that there is a clear difference in nicotine evaporation depending on the e-juice used, where glycerol has a higher evaporation of nicotine compared to propylene glycol. What is unexpected is that it does not seem to be due to difference in size distribution of the aerosol particles but rather due to the chemical composition.

Popular Abstract

A study in electronic cigarettes – how does nicotine behave?

Most of us have probably seen someone smoke a cigarette and heard about the health effects on both the individual as well as the surrounding people? These cigarettes have been studied in every aspect and laws have been implemented based on the results. A more recent thing to see is someone smoke what is called an electronic cigarette, or e-cigarette. These e-cigarettes are rather new on the market. Instead of smoking tobacco the user smokes what is called e-juice. E-juice is a mixture of compounds (nicotine amongst others) that is heated and cooled rapidly to form liquid drops in the air called aerosol particles. These particles are then inhaled into the mouth and lung of the user. The aim of this work is to shed some light on this invention and study how the nicotine behaves in these aerosol particles.

The research question for this work was to study parameters that affect how the nicotine leaves the aerosol particles. The parameters that will be examined are: choice of e-juice, inhalation flow rate? and the temperature used to heat the e-juice to form the aerosol particles. This work also examines the size distribution of the formed aerosol particles; how big the droplets are when they exit the e-cigarette.

Thanks to the extensive research done on common cigarettes, there is plenty of examples how one can observe these changes. By using a cylindrical glass tube coated with something that binds nicotine, it is possible to see the behavior of nicotine. This method is called diffusion denuder. The e-cigarette smoke travels through this denuder. Once aerosol particles have been introduced into the diffusion denuder it is time to collect the nicotine that has been trapped on the coating. The denuder is cut into 8 different pieces and each piece is individually rinsed into a beaker. Depending on the behavior of how the aerosol particles are introduced into the denuder, one can then observe differences due to the investigated parameters.

A total of nine different e-juices were created to study the effect the e-juice have on nicotine leaving. As main component for the e-juices, propylene glycol (PG) and/or glycerol was used. Water was added as well to see how that affected the results.

Basic aerosol physics is used to size the particles. If a large aerosol particle is trying to make a sharp turn at too high speed it will crash into a wall while a smaller aerosol will make the turn. Try making a sharp turn with a fully filled vs empty shopping trolley and you can feel the difference. Then by seeing where a particle hits the wall it is possible to say how big it must have been. This method of sizing is referred to as impaction.

The main result of this project was that using glycerol in the e-juice gave a much higher release of nicotine from the aerosol compared to using PG. The initial thought to explain this fact was that glycerol containing e-juice must form smaller aerosol particles as this should lead to more nicotine leaving. However, the results from the size distribution experiments showed that regardless of what e-juice was used, the size of the aerosol particles remained rather constant. This indicates that the difference must be on a chemical level. The glycerol evaporates and leave the aerosol particle rather than stays in it compared to propylene glycol.

Finally, no difference in nicotine leaving the aerosol could be observed if one inhaled more rapidly on the device, or heated the e-juice more, indicating once again that it all comes down to the chemical composition of the e-juice. So, however we try to affect the nicotine, unless the e-juice is changed, “in the end it doesn’t even matter”, as Linkin Park sings.

• author: Lundegard, Simon
• supervisor: Jakob Löndahl
• organization: Ergonomics and Aerosol Technology
• course: MAM720 20171
• year: 2017
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering; Chemistry
• keywords: AMS, denuder, e-juice, electronic cigarettes, NGI, nicotine, SMPS
• language: English
• id: 8920807
• date added to LUP: 2017-08-03 10:47:06
• date last changed: 2017-08-03 10:47:06