Solid-Phase Microextraction Mediated Solid-Phase Dielectric Barrier Discharge Vapor Generation–Atomic Fluorescence Spectrometry for Sensitive Determination of Mercury in Seawater

Abstract

A novel method coupling solid-phase microextraction (SPME) to solid-phase dielectric barrier discharge (SPDBD) vapor generation was proposed and used for the sensitive detection of trace mercury (Hg) in seawater with atomic fluorescence spectrometry (AFS) in this work. The method proposed herein offers the unique advantages of integrating desorption and chemical vapor generation into one step, eliminating the use of elution reagents, and reducing the analysis time. SPME with multiwalled carbon nanotubes (MWCNTs) coated on the glass tube was used to extract Hg²⁺ in seawater. The Hg²⁺ was then desorbed and reduced to Hg⁰ vapor by SPDBD, which was detected by cold vapor AFS. The parameters affecting Hg²⁺ extraction, desorption, and vapor generation were studied. The detection limit of Hg²⁺ was 0.0003 μg L^–1, and the relative standard deviation at a Hg²⁺ concentration of 0.05 μg L^–1 was 4.4%. This method also has excellent antimatrix interference ability for Hg²⁺ determination with recoveries between 91.8% and 101.1% in the presence of extremely high concentrations (two million times excess) of coexisting ions. The practicality of this method was also evaluated by analyzing two different certified reference materials of Hg²⁺ in water and several seawater samples with good spike recoveries (94.0%–107.4%). Compared with solid-phase photothermo-induced vapor generation, this method has higher extraction efficiency and higher desorption efficiency without the assistance of heating as well as a lower detection limit of Hg²⁺, which is capable of performing trace Hg analysis in seawater.