Quantitative chemical assay of nanogram-level aerosol collected from UAS platforms
Zhang, Qi — University of California, Davis
Area of research
We developed a micronebulization-aerosol mass spectrometry technique that allows us to extract the small mass of ambient particles that uncrewed aerial systems (UAS) can collect, aerosolize the resulting low-volume liquid extract, and sample that aerosol to quantitatively determine the mass concentration of different chemical components present in the particles. We applied this technique to particle samples collected by a fixed-wing UAS as well as on the ground, and were able to accurately reproduce the mass concentrations of organic and inorganic material that was measured in real time by a separate technique.
Our micronebulization-aerosol mass spectrometry technique allows for general improvements to offline analyses of ambient particulate matter (PM) (e.g., particles collected onto filters). Our technique requires significantly lower PM mass and extracted PM sample volumes compared to standard offline, aerosol mass spectrometry techniques, allowing for significantly shorter sampling durations while providing quantitative chemical information.
We have developed a micronebulization-aerosol mass spectrometry (MN-AMS) technique that combines isotopically labelled internal standardization, micronebulization, and aerosol mass spectrometry for quantitative analysis of nanogram-level PM in liquid samples. Compared to standard nebulization techniques that can required milligrams of particulate matter (PM) and several milliliters of liquid PM extract, our MN-AMS technique works with nanogram levels of PM in microliters of solution. Additionally, the use of an isotopically labelled internal standard allows for quantitative analysis of ambient PM without the need for external validation. This technique was applied successfully to PM samples collected from uncrewed atmospheric measurement platforms (UxS) at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility's Southern Great Plains observatory and provided chemical information that agrees well with real-time data from a co-located aerosol chemical speciation monitor (ACSM) as well as offline data from a secondary ion mass spectrometer (SIMS). The MN-AMS technique has broad applicability to offline AMS analyses, offering the potential to reduce PM sampling times and improve the time resolution of offline measurement campaigns.