The composition of PM2.5 aerosols is extremely complex, containing about 20-50% of organic components, including alkanes, alkenes, aromatics, aldehydes, ketones, acids, PAHs, etc. To identify and quantify organic constituents on PM2.5 aerosols, a highly efficient separation technique with superb resolution is required. Comprehensive GC×GC techniques have evolved rapidly into a powerful separation means in the last decade, with superior resolution far beyond conventional chromatography. The basic working principle of GC×GC is to use two columns in-series with different chemical forces to interact with analytes, resulting in orthogonal separation and thus high peak capacity. The most important component in GC×GC is the modulator which connects and also coordinates primary and secondary columns to perform 2D separation. Its role is to periodically enrich and focus effluents from the primary column to form pulsed sample slices which are then sent to the secondary column for further separation. Due to the rather narrow peak width of each sample slice, ToF-MS with much faster data sampling rates than q-MS is utilized to form the system of GC×GC-ToFMS. In 2018, using solvent extraction to combine with GC×GC-ToFMS, we were able to identify 7 phthalates and 3 phosphorous fire retardants (PFRs) from urban (Banqiao district) PM2.5 urban samples. As a result, in addition to the well-known intake channels of oral and skin contact, inhalation of fine particles in polluted air is another channel to pose a health risk. Other than solvent extraction of PM2.5 filter samples, a new technique of thermal desorption aerosol gas chromatography (TAG) is also undergone development in my research group aiming at on-line measurement of PM2.5 in the field to shed light to the formation of secondary organic aerosols (SOA) and source identification. Source markers or profiles of traffic, industrial, biomass burning, and the differentiation of domestic and transboundary PM2.5 events can then be realized. Our second goal is to enhance resolution and sensitivity of GC×GC-ToFMS. By choosing proper column combination and fine-tuning the modulation variables, the improved resolution and sensitivity can facilitate detection of trace level of complex composition of SOA, such as highly oxygenated organic compounds due to prolonged photochemistry. The sensitivity and identification of selective polar compounds can be further elevated through the means of derivatization prior to GC×GC analysis.
|Effective start/end date||1/08/20 → 31/07/21|
UN Sustainable Development Goals
In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This project contributes towards the following SDG(s):
- Comprehensive Two Dimensional Gas Chromatography - Mass Spectrometry (GC×GC-MS)
- Thermal Desorption Aerosol Gas Chromatography(TAG)
- Secondary Organic Aerosols(SOA)
- Phosphorous Fire Retardants(PFRs)
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