Development Of New Methods For Mass Spectrometric Analysis Of Human Exhaled Particles

Aerosol particles are generated in human airways and leave the body in the exhaled air.The particles that are originated from the respiratory tract can provide helpful information?e.g.,particle number concentrations,size distributions and chemical composition?for disease diagnosis,environmental exposure assessment,etc.To utilise any information such as The work reported in this thesis is focused on developing new online analysis methods of organic aerosol particles.In this study,the application of single particle aerosol mass spectrometry?SPAMS?to obtain size-resolved distribution and chemical fingerprint of exhaled particles was demonstrated.In addition,a novel,custom-built secondary nano-electrospray ionization?Sec-nanoESI?source is coupled with a high resolution Quadrupole Orbitrap Mass Spectrometer?HRMS?and applied to the detection of particulate L-tartaric acid?TA?.Factors affecting the detection of TA particles using Sec-nanoESI-HRMS are systematically investigated and discussed.The most important results are presented as follows:?1?By using SPAMS,the number concentration of exhaled particles was 2270–10430 L^-11 and the limit of detection?LOD?for obtaining a representative size-resolved distribution profile was25000 particles,which means approximately 10 L of breath sample was required for the analysis.Regarding the chemical fingerprints,it was speculated that the composition were attributed to the exhaled breath and the inhaled air.The particle loss ratio of gas bag sampling system was70–95%.The results suggested that gas bag sampling system with homemade thermostat maybe lead to particle losses and require to be optimized.?2?Regarding Sec-nanoESI-HRMS,temperature of the ion transport capillary has the most pronounced impact on ion signal intensity and may be attributed to more efficient desolvation and ionization;the normalized collision energy applied during MS²-PRM measurements can also be tuned to obtain optimal fragmentation for more specific and sensitive quantitative analysis.Satisfactory correlations have been observed between the ion signal intensity with both particle surface area?R²=0.969?and mass?R²=0.967?,suggesting that the present Sec-nanoESI technique may be surface-and/or bulk-sensitive.High sensitivity(detection limit=0.14?g m^-3)and a wide linear range(0.2–2.97?g m^-3)are achieved,demonstrating the potential of Sec-nanoESI-HRMS for real-time atmospheric particulate organic matter measurements.