An innovative sampling device for size-fractionating airborne particulate matter for improved air pollution control of metal(oid)s and polycyclic aromatic hydrocarbons

Abstract

A sampling device was developed for collecting and size-fractionating airborne particulate matter (PM). A low-volume cascade system with polytetrafluoroethylene membrane filters (PM₁₀, PM_2.5, and PM_0.1) connected to an ultrapure-water trap was used to retain the PM_<0.1 fraction that passed through the filters. In the collected samples, metal(oid)s and platinum group elements (PGEs) were determined by inductively coupled plasma mass spectrometry after microwave-assisted digestion using a mixture of acids. Polycyclic aromatic hydrocarbons (PAHs) were extracted with a solvent mixture of acetone and petroleum ether, assisted by mechanical shaking and determined by gas chromatography mass spectrometry. The analytical methods were optimised and validated using the urban PM Standard Reference Material 1648a. Measurement repeatability and accuracy were 6% and 2% for metal(oid)s and PGEs, and 3% and 6% for PAHs, respectively. Field emission scanning electron microscopy analysis confirmed that the sampling device efficiently fractionated airborne PM to nano-sized particles. The sampling device was successfully applied to collect PM, enabling effective air pollution monitoring in urban areas. Analysis revealed that metal(oid)s were most abundant in PM₁₀, while those originating from traffic were also elevated in PM_<0.1. High-molecular-weight PAHs were distributed between PM₁₀ and PM_2.5 fractions. The sampling device provides valuable insights into the chemical composition of (ultra)fine particles, overcoming the limitations of filter-based PM fractionation and providing improved air pollution control for nanoparticle-bound pollutants.