Electrochemical arsine generators for arsenic determination

Area of Science:

• Analytical Chemistry
• Electrochemistry
• Environmental Science

Background:

• Arsine generation is crucial for sensitive arsenic (As) determination.
• Traditional electrochemical arsine generators (EAGs) often rely on specific electrode materials and conditions.
• There is a need for greener and more versatile EAGs for arsenic analysis.

Purpose of the Study:

• To introduce and evaluate two novel electrode materials, aluminum and highly oriented pyrolytic graphite (HOPG), for electrochemical arsine generation.
• To demonstrate the effectiveness of these EAGs for sensitive and selective arsenic determination.
• To explore the potential for arsenic speciation using these new EAG systems.

Main Methods:

• Development and construction of two EAGs: one utilizing aluminum in a constant voltage mode and another using HOPG.
• Electrochemical arsine generation coupled with gas phase chemiluminescence (GPCL) detection using ozone.
• Analysis of As(III) and As(V) in prepared standards and real-world groundwater samples.

Main Results:

• The aluminum-based EAG operates effectively in a novel constant voltage mode, ensuring cathode longevity.
• The HOPG-based EAG shows differential response to As(III) and As(V), enabling speciation.
• Attractive limits of detection (LODs) were achieved: 1.4 μg/L for Al-EAG and 1.0-1.9 μg/L for HOPG-EAG.
• High precision (2.1-2.4% RSD) and sample throughput (12/h) were demonstrated for both systems.
• Results from groundwater samples showed excellent agreement with induction coupled plasma-mass spectrometry (ICP-MS).

Conclusions:

• Aluminum and HOPG are effective and novel electrode materials for electrochemical arsine generation.
• These EAG systems offer green, sensitive, and selective methods for arsenic determination and speciation.
• The findings challenge conventional wisdom regarding electrode material selection for electrochemical hydride generation.