On-line electrokinetic extraction and electrochemical hydride generation coupled with atomic fluorescence spectrometry for inorganic arsenic speciation in water samples

Abstract

In this paper we discuss an on-line electrokinetic extraction and electrochemical hydride generation system for inorganic arsenic speciation developed using an H-type integrated cell. The integrated cell, mainly consisting of a working chamber and an auxiliary chamber, was used as both an electrokinetic extraction and an electrochemical hydride generation unit. The As(V) ions in the sample solution was firstly extracted into the working chamber of the H-type integration cell and reduced into As(III). Subsequently, the integrated cell was converted to an electrochemical hydride generation unit to generate arsine by changing power supply and the direction of the electrical field. Finally, the arsine generated in the working chamber was separated using a gas–liquid separator and detected by atomic fluorescence spectrometry. Potential factors that affect the extraction and hydride generation were investigated in detail. The precision (RSD, n = 10) ranged from 2.3–3.5% for peak area response for As(V) at the 2 μg L⁻¹ level. A detection limit (3σ) of 0.020 μg L⁻¹ As(V) was achieved. The recoveries of three samples ranged from 98 to 104%. The results obtained by the method for As(V) in the certified reference material (BW3210) agreed well with the certified values. The proposed method was successfully applied to pre-concentration and speciation of arsenic species in natural water samples.