A Study of Free Amino Acids Analysis in the Atmosphere Using LC-HRMS

This study aims to investigate both qualitative and quantitative methods for the simultaneous multicomponent and trace analysis of free amino acids (FAAs) in atmospheric particulate matter using LC-HRMS. The method was applied by collecting samples to assess the actual occurrence of FAAs in the atmosphere. The analytical technique utilized was LC-HRMS (Orbitrap), with a focus on the Amino Acid column, which demonstrated excellent separation performance, with peak detection beginning approximately five minutes after sample injection. A total of 15 FAA species were analyzed within a 20-minute run time. Accelerated solvent extraction (ASE) was effective, and the relatively low recovery rate was compensated for by using 15 internal standards. The matrix test confirmed that the method can be applied to actual particulate matter (PM) samples. Analysis of 13 PM samples collected over a two-month period revealed that L-valine was the most abundant FAA. FAAs in fine particulate matter accounted for approximately 6% of the total FAA, with 72% of this fraction found in ultrafine dust particles. This study advances the analytical method for trace-level detection of FAAs, facilitating their identification and quantification in atmospheric particulate matter.