Novel Dielectric Barrier Discharge Trap for Arsenic Introduced by Electrothermal Vaporization: Possible Mechanism and Its Application.

Abstract

In this work, a novel integrated dielectric barrier discharge (IDBD) reactor coupled to an electrothermal vaporizer (ETV) was established for arsenic determination. It is for the first time gas-phase enrichment (GPE) was fulfilled based on the hyphenation of ETV and DBD. The mechanisms of evolution of arsenic atomic and molecular species during vaporization, transportation, trapping, and release processes were investigated via X-ray photoelectron spectroscopy (XPS) and other approaches. Tentative mechanisms were deduced as follows: the newly designed DBD atomizer (DBDA) tube upstream to the air inlet fulfills the atomization of arsenic nanoparticles in vaporized aerosol, leading to free arsenic atoms that are indispensable for forming arsenic oxides; the DBD trap (DBDT) tube traps arsenic oxides under an O2-domininating atmosphere and then releases arsenic atoms under H2-dominating atmospheres. In essence, this process is a physical-chemical process rather than an electrostatic particle deposition. Such a trap and release sequence separates matrix interference and enhances analytical sensitivity. Under the optimized conditions, the method detection limit (LOD) was 0.04 mg/kg and the relative standard deviations (RSDs) were within 6% for As standard solution and real seafood samples, indicating adequate analytical sensitivity and precision. The mean spiked recoveries for laver, kelp, and Undaria pinnatifida samples were 95-110%, and the results of the certified reference materials (CRMs) were consistent with certified values. This ETV-DBD preconcentration scheme is easy and green and has low cost for As analysis in seafood samples. DBD was proved a novel ETV transportation enhancement and preconcentration technique for arsenic, revealing its potential in rapid arsenic analysis based on direct solid sampling ETV instrumentation.