Battery-Operated Atomic Emission Analyzer for Waterborne Arsenic Based on Atmospheric Pressure Glow Discharge Excitation Source

Abstract

In this paper, a sensitive atomic emission spectrometer (AES) based on a new low power and low argon consumption (<8 W, 100 mL min) miniature direct current (dc) atmospheric pressure glow discharge (APGD) plasma (3 mm × 5 mm) excitation source was developed for the determination of arsenic in water samples. In this method, arsenic in water was reduced to AsH by hydride generation (HG), which was then transported to the APGD source for excitation and detected by a compact CCD (charge-coupled device) microspectrometer. Different parameters affecting the APGD and the hydride generation reactions were investigated. The detection limit for arsenic with the proposed APGD-AES was 0.25 μg L, and the calibration curves were found to be linear up to 3 orders of magnitude. The proposed method was successfully applied to the determination of certified reference material (GBW08605), tap water, pond water, groundwater, and hot spring samples. Measurements from the APGD analyzer showed good agreement with the certified value/values obtained with well-established hydride generation atomic fluorescence spectrometry (HG-AFS). These results suggest that the developed robust, cost-effective, and fast analyzer can be used for field based arsenic determination and may provide an important tool for arsenic contamination and remediation programs.

Ultrasensitive Determination of Selenium and Arsenic by Modified Helium Atmospheric Pressure Glow Discharge Optical Emission Spectrometry Coupled with Hydride Generation

“…It should be noted that there was a voltage drop across the ballast resistors that was not included in this measurement and was large enough to make the total resistance positive. As shown in Figure b, APGD displayed a negative dynamic resistance, as has also been reported for other atmospheric pressure glow discharges sources. , Although negative resistance was commonly seen as an indication of an arc rather than of a glow discharge, APGD has been reported to still operate in the glow regime. , The observed negative resistance was in part ascribed to Joule heating, the extent of which grew with increasing current density; in turn, the concomitant increase of temperature lowered the density of the gas and therefore reduced the potential required to maintain a glow discharge . As shown in Figure a, when the SS cathode tube was not embedded into tube A1, the cathode surface coverage increased with increasing discharge current, which precluded the concomitant growth of the current density .…”

“…The reaction mixture was subsequently passed into the GLS and merged with the carrier gas (He) for separation of the gaseous products from the postreaction solution. To prevent hydride-doped liquid components, which may cause fluctuations and energy drops of the discharge, from entering the discharge area, the product of the HG system was passed through a CaCl 2 -filled drying unit prior to APGD. , Figure b shows the core design of the self-made radiation source, indicating that this system was comprised of three fused silica tubes (A1–A3) of different diameters (A1, 1.6 mm i.d. × 3 mm o.d.…”

“…Recently, miniaturized plasmas have attracted increased attention as alternative radiation sources for OES because of their numerous advantages, including a small footprint and low operating costs related to energy and gas consumption. − Such plasmas include, but are not limited to, electrolyte-as-cathode glow discharge (ELCAD), liquid sampling–atmospheric pressure glow discharge (LS-APGD), solution cathode glow discharge (SCGD), atmospheric pressure glow discharge (APGD), flowing liquid cathode–atmospheric pressure glow discharge (FLC-APGD), and dielectric barrier discharge (DBD) . To guarantee that the above radiation sources can provide effective excitation of some elements, coupling with separation/preconcentration techniques (such as solid-phase extraction and chemical vapor generation) can improve the determination performance of miniaturized plasmas for some elements. ,, Among the numerous chemical vapor generation techniques reported to date, hydride generation (HG) can efficiently extract target elements from samples with minimum sample pretreatment . By coupling with an HG system, the highly sensitive determination of some elements, such as arsenic, antimony, and so on, is achieved on the basis of APGD. ,, The emission sensitivities of arsenic and antimony in HG-APGD are further enhanced by adopting a novel interrupted gas flow (IF) technique .…”

“…To guarantee that the above radiation sources can provide effective excitation of some elements, coupling with separation/preconcentration techniques (such as solid-phase extraction and chemical vapor generation) can improve the determination performance of miniaturized plasmas for some elements. ,, Among the numerous chemical vapor generation techniques reported to date, hydride generation (HG) can efficiently extract target elements from samples with minimum sample pretreatment . By coupling with an HG system, the highly sensitive determination of some elements, such as arsenic, antimony, and so on, is achieved on the basis of APGD. ,, The emission sensitivities of arsenic and antimony in HG-APGD are further enhanced by adopting a novel interrupted gas flow (IF) technique . The above results therefore demonstrate that the excitation efficiency of elements is significantly enhanced by improving the way or efficiency of the analyte entering into the microplasma.…”

Point Discharge Microplasma Optical Emission Spectrometer: Hollow Electrode for Efficient Volatile Hydride/Mercury Sample Introduction and 3D-Printing for Compact Instrumentation

“…In OES, various microplasmas have been used as excitation sources for compact instrumentation because of their unique advantages, including small size, low gas and power consumption, easy operation, and low manufacturing and running costs. − These excellent characteristics also make them suitable for real-time and field analysis. Various types of microplasma-based excitation sources have been reported in recent years, such as microdischarge plasma including glow discharge (GD), − corona discharge (CD), dielectric barrier discharge (DBD), − and point discharge (PD). , They have been predominantly used for OES determination of various analytes, such as metal elements, inorganic anions, volatile carbon-containing compounds, and halohydrocarbons. − …”