Helium and Proton Particle-Induced X-Ray Emission (PIXE) for Characterization of PM2.5 from Surabaya, Indonesia

Abstract

Generally, particle-induced X-ray emission (PIXE) analysis is performed using protons as the incident projectiles. In this study, helium ions were used for inducing X-ray emission to improve the detection limit for the characterization of light elements in the PM2.5 fine fraction. The sampling was conducted for 24 h using a Gent stacked filter unit sampler at an industrial site in Surabaya, Indonesia. The samples were analyzed by PIXE using a 4-MV Van de Graaff accelerator at Kyoto University. Both helium and protons were used in the analysis to obtain optimal results, and 21 elements were detected in the samples. Notably, the use of helium particle-induced X-ray emission was more suitable for Na, Mg, Al, and Si than protons. Moreover, the sensitivity and limit of detection for these elements were enhanced using helium ions. Validation was performed using standard reference material NIST 2783 air particulates on filter media, and the results were in good agreement. Using both He-PIXE and H-PIXE, heavy metals, crustal elements, and other elements were identified that exhibited the characteristics of PM2.5 collected in Surabaya, Indonesia. Further statistical analysis and receptor modeling are required to identify the possible pollutant sources of PM2.5.