Enhancement of emission from arsenic in enclosed solution anode glow discharge system using hydrogen‑helium mixture and propionic acid - A preliminary study

Abstract

The use of solution anode glow discharge (SAGD) operating in hydrogen‑helium mixture as an excitation source for optical emission spectrometry (OES) of arsenic (As) in solution was evaluated. An enclosed structure was adopted, and the hydrogen‑helium mixture was fed into the discharge chamber with non-electrode hollow channel. The hydrogen‑helium plasma integrated the functions of vapor generation, atomization and excitation of As. Thus, the detectable element scope of SAGD-OES was extended to As, without coupling any separation and/or enrichment technique, such as hydride generation (HG). The effects of the type and concentration of small organic molecules were investigated. It was revealed that propionic acid (0.1%, v/v) had the best response amplification effect, up to 3.4 times. The detection limit (DL) of the SAGD-OES could reach 28 μg L−1, which is better than that of the fully open-to-air discharge system. For As, SAGD was prone to chemical interferences induced by transition metal elements to a higher degree than that induced by alkali metals and alkaline earth metals, which is similar to those reported in chemical vapor generation (CVG).