Microplasma Optical Emission Spectrometry with MWCNT-Assisted Extraction and Ultrasonic Nebulization-Enhanced Photochemical Vapor Generation for Sensitive Determination of Trace Heavy Metals in Seafood

Field analysis of heavy metals in seafood is crucial for assessing the hazards and potential risks associated with human exposure to heavy metals through dietary intake. However, a low analyte concentration and complex pretreatment procedures pose significant challenges for microplasma-optical emission spectrometry (OES). Herein, multiwall carbon nanotubes (MWCNTs)-assisted extraction and ultrasonic nebulization-enhanced photochemical vapor generation (PVG) are integrated into a point discharge microplasma-OES system for field analysis of trace Hg, Fe, Co and Ni in seafood. With MWCNTs as solid support and formic acid as elution solvent, matrix solid-phase dispersion extraction for fish can be completed within 10 min by a self-designed pretreatment unit, achieving the extraction efficiencies of 84–91%. The extract is directly ultrasonic nebulized for improving the following VG efficiency to 94–97%, benefiting from the increasing gas–liquid interface to promote the generation of reductive free radicals. Under the optimized conditions, the detection limits for Hg, Fe, Co, and Ni are 0.3, 0.3, 0.2, and 0.5 μg L^–1, respectively. The accuracy and practicability of the present device are verified by measuring several certified reference materials and real seafood samples. By virtue of simple operation, short pretreatment time, favorable portability, and detection sensitivity, this device provides an innovative tool for field monitoring of heavy metal pollution in seafood.