High Sensitivity Analysis of Selenium by Ultraviolet Vapor Generation Combined with Microplasma Gas Phase Enrichment and the Mechanism Study

Ultraviolet vapor generation (UVG), as an environmental/user-friendly and efficient sampling approach, was first combined with the gas phase enrichment of Se by dielectric barrier discharge (DBD) microplasma. Volatile Se species from UVG, being much more complicated than conventional hydrides, can be trapped quantitatively (similar to 100%) on the quartz surface of DBD tube under O-2-containing atmosphere and released (similar to 100%) under H-2-containing atmosphere. The absolute detection limit (LOD) for Se was 4 pg (injection volume = 1.2 mL), and the linear (R-2 > 0.995) range was 0.05-50 mu g/L. The results were in good agreement with those of certified reference materials (CRMs) of water and soil samples, and spiked recoveries for real samples were 90-102% with 1-10% relative standard deviations (RSDs). By gas phase analyte enrichment, the proposed method improved analytical sensitivity (peak height) by 16 times. The mechanism was deduced that dominating SeCO species besides H2Se generating from UVG were all trapped on the DBD quartz tube surface as SeO2 or selenite and then released/transported as atoms to the detection zone. The combination of UVG and DBD can facilitate the green uses, miniaturization, and portability revealing its promising potential in field elemental analysis.