Rapid Elemental Analysis of Aerosols Using Atmospheric Glow Discharge Optical Emission Spectroscopy

摘要

A new, low-cost approach based on the application of atmospheric radio frequency glow discharge (rf-GD) optical emission spectroscopy (OES) has been developed for near real-time measurement of multielemental concentration in airborne particulate matter. This method involves deposition of aerosol particles on the tip of a grounded electrode of a coaxial microelectrode system, followed by ablation, atomization and excitation of the particulate matter using the rf-GD. The resulting atomic emissions were recorded using a spectrometer for elemental identification and quantification. The glow discharge plasma was characterized by measuring spatially resolved gas temperatures (378 – 1438 K) and electron densities (2 – 5 × 10¹⁴ cm⁻³). Spatial analysis of the spectral features showed that the excitation of the analyte occurred in the region near the collection electrode. The temporal analysis of spectral features in the rf-GD showed that the collected particles were continuously ablated; the time for complete ablation of 193 ng of sucrose particles was found to be approximately 2 s. The system was calibrated using 100 nm particles containing C, Cd, Mn, and Na, respectively. Our method provides limits of detection in the range of 0.055 – 1.0 ng, and a measurement reproducibility of 5 – 28%. This study demonstrates that the rf-GD can be an excellent excitation source for the development of low-cost hand-held sensors for elemental measurement of aerosols.