Generation of Electronic Cigarette Aerosol by a Third-Generation Machine-Vaping Device: Application to Toxicological Studies

This method can help answer key questions in the field of inhalation toxicology, with regards to the electronic cigarette aerosol exposure effect continuum. The main advantage of this technique is the computer-controlled electronic cigarette aerosol exposure scenarios included automated representative vaping topography profiles. After setting up the equipment in a well-ventilated area, weigh a new clean 25-millimeter filter and record the weight.

Place the filter in a cassette. Place the cassette in line with the personal sampling pump in a flow meter adequate to test for a flow of one liter per minute. To begin preparing the electronic cigarette device, screw the atomizer into the tank base, add two to three drops of e-cig liquid into the atomizer, and ensure that the cotton is saturated to avoid a dry burn.

Insert the tank sleeve into the tank, and then screw the tank base with the atomizer into the tank sleeve. Screw the assembled tank onto the e-cig unit. Make sure the tank opening is facing upwards, and put the cover in place on top of the tank.

Gently place the e-cig unit of the base plate under the solenoid valve. Using a two-way valve attachment and a piece of tubing, connect the end of the e-cig unit to the lower part of the condenser. Make sure that the upper end of the condenser is connected correctly to the aerosol generating system and the aerosol exposure chamber.

Verify that the aerosol concentration measurement instrument is in place at the exit of the aerosol exposure chamber. Remove the tank cover and fill the tank with 10 milliliters of e-cig liquid composed of equal parts propylene glycol and vegetable glycerin. Then replace the tank cover.

On the day of the experiment, power on the computer and the aerosol concentration measurement instrument. Launch the operating software. Click on experimentation session, and select the appropriate study.

Choose the template for the e-cig experiment. In the new experiment window, enter a name for the experimental session. In the experiment properties window, type in the operator initials in the operator box, and click OK.After this, start the calibration wizard.

In the channel calibration window, confirm that there is a check mark in the aerosol concentration measurement instrument box. Then click next. In apply value window, click next.

Enter a target value input of zero grams per meter cubed. Place the t-shaped calibration insert into the slot to complete the calibration process. And then press next to get to the following window.

Enter the value from the aerosol concentration measurement instrument and press next. Review the calibration results window and click next. To complete the calibration, click finish.

Next, test pumps one and two as outlined in the user manual. When asked to confirm the start of recording continuous data, click yes. When asked to start the default profile, click yes.

If performing an in vivo inhalation study, place the mice in a whole-body exposure chamber. Immediately go to the profiles window and right-click on the desired profile. Scroll down to start task to initiate a bias flow of fresh air inside the exposure chamber.

When ready to initiate the e-cig aerosol generation and exposure experiment, right-click on the desired profile in the profiles window. Scroll down to start profile, and left-click to select it. Record the concentration measured by the aerosol concentration measurement instrument.

Make sure that the e-liquid is available in the tank for the entire duration of the exposure. You will be able to see the e-cig aerosol going in the chamber. After reaching the desired exposure duration, stop the experiment by right-clicking on the profile.

Scroll down to stop profile, and left-click to select it. Ensure that the bias flow is initiated immediately following the completion of the exposure profile. Remove the subjects from the exposure chamber and return them to their housing cage and room.

Then detach the cassette with the filter from the pump and record the time it was removed. Place the filter in a desiccator and let it dry for at least 48 hours. Weigh the filter with the accumulated e-cig aerosol particles and record the weight.

After calculating the total particulate matter concentration, record the mass accumulated on the filter. Pour the e-liquid out of the e-cig tank and empty the condenser using the attached syringe. Make sure that the atomizer coil did not burn during the experiment.

Detach the pump heads and remove the connectors and valves. Wipe off any excess e-liquid or accumulated moisture using either a cotton swab or tissue. Then clean the whole-body exposure chambers following the manufacturer's instructions.

Make sure to remove any condensed e-liquid from the chamber's surfaces. In this study, e-cig aerosol is generated to study its toxicological impact. The data seen here was recorded after a two-hour exposure session with only the carrier solvent's e-liquid base.

As expected, the total particulate matter concentration of the aerosol is seen to increase in the exposure chamber when a higher e-cig voltage is used. An experimental e-cig exposure environment is then created based on current information regarding e-cig consumer personal preferences, and is subsequently characterized. Over a two-hour exposure period, this profile draws a larger number of puffs, and allows for a higher total volume to be sampled compared to the previously-employed profile.

Averages obtained under this profile for different e-liquids seem to indicate that the presence of nicotine in cinnamon flavor may have a negative effect on the particulate mass per puff. A chemical analysis of the e-cig aerosol generated with this topography profile reveals that in addition to the expected nicotine and cinnamaldehyde, other compounds such as acrolein, catechol, and benzothiazole are present. These chemicals are known respiratory irritants, and show the complexity of the aerosol composition once the e-liquid is heated and aerosolized.

Once mastered, this exposure can be completed in two and a half hours if it is performed properly. While attempting this procedure, it is very important to record the aerosol concentration using the aerosol concentration measuring device at least every 30 minutes. Following this procedure, other air samples can be collected in order to answer additional questions related to the physical and the chemical characteristic of the electronic cigarette aerosol.

After its development, this exposure system paved the way for researchers in the field of inhalation toxicology to explore toxicological responses induced by inhaled electronic cigarette aerosol in rodents. After watching this video, you should have a good understanding on how to expose rodents by inhalation to electronic cigarette aerosol via an exposure system with automated vaping topography profile. Don't forget that working with e-liquid and electronic cigarette aerosol can be hazardous, and precautions including personal protective equipment such as lab coat, glove, and safety glasses should always be taken while performing this procedure.