Preconcentration and Atomization of Arsane in a Dielectric Barrier Discharge with Detection by Atomic Absorption Spectrometry

Abstract

Atomization of arsane in a 17 W planar quartz dielectric barrier discharge (DBD) atomizer was optimized, and its performance was compared to that of a multiple microflame quartz tube atomizer (MMQTA) for atomic absorption spectrometry (AAS). Argon, at a flow rate of 60 mL min(-1), was the best DBD discharge gas. Free As atoms were also observed in the DBD with nitrogen, hydrogen, and helium discharge gases but not in air. A dryer tube filled with NaOH beads placed downstream from the gas-liquid separator to prevent residual aerosol and moisture transport to the atomizer was found to improve the response by 25%. Analytical figures of merit were comparable, reaching an identical sensitivity of 0.48 s ng (-1) As in both atomizers and limits of detection (LOD) of 0.15 ng mL(-1) As in MMQTA and 0.16 ng mL(-1) As in DBD, respectively. Compared to MMQTA, DBD provided 1 order of magnitude better resistance to interference from other hydride-forming elements (Sb, Se, and Bi). Atomization efficiency in DBD was estimated to be 100% of that reached in the MMQTA. A simple procedure of lossless in situ preconcentration of arsane was developed. Addition of 7 mL min(-1) O2 to the Ar plasma discharge resulted in a quantitative retention of arsane in the optical arm of the DBD atomizer. Complete analyte release and atomization was reached as soon as oxygen was switched off. Preconcentration efficiency of 100% was observed, allowing a decrease of the LOD to 0.01 ng mL(-1) As employing a 300 s preconcentration period.

Ultratrace determination of arsenic by hydride generation atomic absorption spectrometry with preconcentration on gold nanoparticles

“…A sensitivity of 0.43 AE 0.01 s ng À1 As was found in an Ar atmosphere which was well comparable to the value reported recently in the common (non-modular) MMQTA with Ar carrier gas (0.48 AE 0.003 s ng À1 As). 18 Even higher sensitivity (0.53 AE 0.01 s ng À1 As) was found in the H 2 atmosphere.…”

“…It is well known that controlled addition of oxygen into the MMQTA in the form of either air or pure O 2 enhances the sensitivity of determination of hydride forming elements, especially As and Se. 17,18 Oxygen reacts with excess of hydrogen to produce H radicals that are responsible for efficient hydride atomization as well as protecting free atoms from decay reactions. 3,30 The oxygen demand is dependent mainly on carrier gas composition and atomization temperature.…”

“…10 Complete arsane trapping followed by quantitative release of preconcentrated arsenic species was also reported in the case of cryotrapping 19 and in situ preconcentration in the DBD atomizer. 18 In contrast, preconcentration of As at the bare quartz surface reached a preconcentration efficiency of 50% only. 15 The performance of the preconcentration step could not be further improved despite the fact that the reason for incomplete analyte preconcentration was identied and understood in a follow up study.…”

“…In situ trapping in a DBD atomizer can be taken as another example of arsane trapping at the quartz surface. 18 Also cryotrapping makes use of hydride preconcentration at quartz, providing the U-tube is not packed with any chromatographic lling. Using the cryotrapping approach, arsane trapping in a bare quartz U-shaped capillary was investigated 19 while a quartz U-tube packed with Chromosorb was utilized in another study.…”

In Situ Dielectric Barrier Discharge Trap for Ultrasensitive Arsenic Determination by Atomic Fluorescence Spectrometry

“…Such an HG-DBD-AFS system was applied to measure ultratrace arsenic in surface water, with a 1 ng/L LOD via 8-fold enrichment in 20 mL sampling volume. Soon after, Kratzer et al used a planar DBD atomizer coupled to HG-AAS to enrich arsenic based on similar principle, and confirmed that arsenic analyte can be retained in the DBD atomizer by the Ar–O 2 discharge and subsequently released by the Ar–H 2 discharge. They also realized a preconcentration efficiency of ∼100%, reaching 10 ng/L LOD via 300 s preconcentration.…”