| dc.description.abstract | The importance of studying particle-bound components in aerosol samples has been highlighted during the COVID-19 pandemic, when people tried to stop the spread of droplet-bound viruses by wearing face masks. While the importance of these droplet/particle-bound analytes is well-known, their study has been hampered by the lack of a proper device for sampling and detection of these compounds. All these reasons explain the need for development of an extraction device that, not only traps droplet/particles from aerosol samples, but also preconcentrates free and gaseous analytes to enable comprehensive analysis of aerosol samples.
Among various microextraction methods, the needle-trap device (NTD) is the best candidate for entrapment and investigation of particle or droplet-bound compounds. The dynamic sampling and packed design can improve the role of NTD as a trapping device. Still, the filtration efficiency of NTD packed with commercial sorbent particles is limited due to the large diameter of packing material and can be improved by addition of an appropriate filter into the NTD. To this end, in this thesis, initially the filter with required criteria was developed and optimized. Then, the filter was packed inside the needle, in addition to the commercial sorbent particles to trap droplets/particles and extract gaseous compounds, respectively. The prepared NTD was then applied to study the aerosol sample including breath, air pollutants, sprays and sparkling beverages. To compare total and free (gas-phase) concentrations, the results from filter-incorporated NTD was compared to the results of solid-phase microextraction (SPME) methods.
After device development, free (from SPME results) versus total (from NTD results) concentration of fragrance compounds in different types of sprays was studied. In this study, the trend of concentration of fragrances over a time span after administration and the effect of air circulation with fan on air pollution was studied and reported. It was shown that the actual exposure concentration to fragrances during application of sprays can be much higher than gas-phase concentration. In another study, the concentration of aroma compounds in real consumer experience condition from sparkling beverages was studied and it was shown that the type and extent of carbonation and the physiochemical properties of aroma compounds plays influential roles on the distribution of these components between gas and droplet phase.
The next sections were dedicated to study of the most critical aerosol sample: breath samples and air pollutions. Based on the importance of these samples, various breath samples were studied from lung cancer patients or volunteers exposed to indoor air pollutants. The results showed that polar compounds have high tendencies to remain inside breath droplets, which mean during studying only gas-phase breath this type of information can be lost. For air pollution samples, it was revealed that less-volatile compounds such as large PAHs can be attached on the surface of smoke particles and carried to various locations by wind.
As the conclusion, it was shown that the developed NTD device is efficient and green for comprehensive study of aerosol samples. Among various potential applications, breath and air pollution provided the most critical and vital information, opening a new window to a novel type of information which was missing in previous studies in this area. The device is cheap and re-usable which highlights its environmental friendliness. While initial studies provided promising results, the application of NTD for aerosol samples is in its initial stages and there is a wide window of opportunities for future studies. The type and characteristics of filter can be varied and other types of samples can be studied. In the field of breath analysis, the application of studying droplet-bound compounds for diagnostic and treatments can be an opportunity for non-invasive and fast sampling. | en |
