Characterization of Pollen using Microscopy and EGA-MS following Sequential Solvent Extraction

Pollen has been identified as a significant contributor to airborne particulate matter (PM), and studies have shown that despite pollen's large size, sub-pollen particles are substantial contributors to PM2.5, potentially making them essential components of the carbonaceous atmospheric PM. Understanding the contribution and impact of pollen on air PM and organic carbon is vital as these sub-pollen particles can be transported over long distances, affecting health, climate change, and agriculture. A method involving careful extraction and analysis techniques to isolate markers that will enable the chemical speciation of organic carbonaceous PM, aid in providing a comprehensive chemical composition of pollen, and enable DNA-based identification of outdoor sub-pollen particles in air PM will be applied. In this study, pollen grains underwent a series of less aggressive extraction/washing steps, impacting both hydrophilic and hydrophobic fractions. The sequential Soxhlet extraction with solvents of decreasing polarity, i.e., room temperature water, hot water, methanol, acetone, and hexane, enabled the separation of carbohydrates and lipids from connective layers of pollen grains. Each extracted fraction and residual pollen grain exine were characterized using microscopic analysis an