Automated oil vapor inhalation exposure system

Data Collection Methods

• Heated crude oil (85 F) was fed to an atomizer by a syringe pump.
• Heated (85 F) dilution air (40 L/min) was mixed with the oil mist from the atomizer.
• To achieve constant relative humidity, custom software set the ratio of dilution air that passed over a heater water bath or bypassed it.
• The oil droplet air mixture was fed into a 1-inch diameter PTFE tube.
• Particle filters removed the droplets after the PTFE tube.
• Particle free COV entered the top of an exposure chamber and exited the bottom.
• The total volatile organic compounds (TVOC) gas concentration was measured inside the exposure chamber with continuous samples by a flame ionizing detector.
• Adjustments were made automatically to the oil injection flow entering the atomizer via custom control software.
• The TVOC monitor was calibrated using benzene, toluene, ethylbenzene and xylene (BTEX) gas as a standard.
• A GC-FID instrument was used to collected additional data on the gas mixture during inhalation exposures.
• Exposure chamber pressure was monitored with a pressure transducer.
• Exposure chamber pressure was automatically maintained at 0 by setting the amount of chamber exhaust air with a mass flow controller hooked to lab. vacuum.
• Exposure chamber temperature and relative humidity was monitored with a probe inside the chamber.
• Exposure chamber CO2 was monitored with a probe placed in the exposure chamber’s exhaust air.
• The custom software automatically controlled TVOC gas concentration, chamber pressure, relative humidity and exposure duration during exposure runs.
• Animal exposures lasting 1 day or 16 days were conducted at a target TVOC gas concentration of 300 PPM, with daily exposure runs lasting 6 hours.