Experimental Investigation on Water Adsorption Using Laser Photoacoustic Spectroscopy and Numerical Simulations

In the present research we propose a model to assess the water vapors adsorption capacity of a SiO₂ trap in the breathing circuit, aiming to reduce the loading of interfering compounds in human breath samples. In this study we used photoacoustic spectroscopy to analyze the SiO₂ adsorption of interfering compounds from human breath and numerical simulations to study the flow of expired breath gas through porous media. As a result, the highest adsorption rate was achieved with a flow rate of 300 sccm, while the lowest rate was achieved with a flow rate of 600 sccm. In the procedure of H₂O removal from the human breath air samples, we determined a quantity of 213 cm³ SiO₂ pearls to be used for a 750 mL sampling bag, in order to keep the detection of ethylene free of H₂O interference. The data from this study encourages the premise that the SiO₂ trap is efficient in the reduction of interfering compounds (like water vapors) from the human breath.