10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Novel Method for Multi-component Continuous Real-time Aerosol Monitoring Using FTIR Spectroscopy for In-vivo Studies
WEI TECK TAN, Subash Krishnan, Patrick Vanscheeuwijck, Philip Morris International Research Laboratories Pte Ltd
Abstract Number: 1735 Working Group: Aerosol Chemistry
Abstract The conduct of in-vivo studies as recommended by test guidelines (e.g. TG413) from the Organization for Economic Cooperation and Development (OECD) requires the test atmosphere to be held as constant as practicable. This is non-trivial especially in cases whereby the test item are complex multi-phase and multi-constituent aerosols from tobacco products or e-liquids.
Classical methods for quantification of non-gaseous key constituents such as determination of the test atmosphere nicotine concentration typically involves sample trapping in an appropriate medium followed by off-line analysis. This is resource intensive and provides only cumulative averages over the period of sample collection. For a more immediate assessment, a real time aerosol characterization method has been developed to quantify key aerosol constituents using Fourier Transformed Infrared (FTIR) spectroscopy.
The setup for sample processing, analysis and extraction from the test atmosphere consists of: 1) A dilutor which dilutes the sample to the concentration within the quantification limits of the FTIR if required, 2) A transfer section with heated tubes to vaporize non-gaseous components of the constituents to be quantified, 3) a heated filter at the end of the heated tubes to remove residual non-gaseous components to avoid damage to the FTIR, 4) a Gasmet FTIR spectrometer and 5) A vacuum pump for pulling the sample from the test atmosphere to the FTIR.
The measured overall IR spectra of the aerosol obtained from the test atmosphere is deconvoluted and compared in real time against reference calibration spectra using proprietary software from Gasmet to quantify the concentration in μg/L for water, propylene glycol, glycerol, and nicotine concurrently. During continuous sampling from the test atmosphere, concentrations of the aforementioned constituents can be quantified simultaneously by the FTIR in approximately every < 6 seconds.
Comparative studies were conducted using aerosol from e-liquids and the IQOS smokeless product whereby nicotine results from the FTIR were found to be within ±20% of the results from validated off-line analysis methods using gas chromatography. It is demonstrated that this method allows for real time quantification of selected key constituents and that can be used as a tool to further characterize the test atmosphere. When used for test atmosphere monitoring, the data generated in real time from the FTIR allows for earlier detection of process deviations and timely interventions which therefore improves the stability of the test atmosphere.