Mercury speciation in sea food by flow injection cold vapor atomic absorption spectrometry using selective solid...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Spectroscopy

Background:

• Mercury speciation is critical for understanding its environmental fate and toxicity.
• Existing methods for mercury speciation can be complex and time-consuming.
• Accurate determination of inorganic and organomercury is essential for risk assessment, especially in food sources like seafood.

Purpose of the Study:

• To develop and validate an on-line system for the separation and preconcentration of inorganic and organomercury species.
• To compare the efficacy of cold vapor atomic absorption spectrometry (CV-AAS) and cold vapor-atomic absorption spectrometry with electrothermal atomization (CV-ETAAS) for mercury speciation.
• To provide a simple yet effective method for determining methylmercury content in seafood samples.

Main Methods:

• An on-line flow injection (FI) system coupled with cold vapor atomic absorption spectrometry (CV-AAS or CV-ETAAS) was employed.
• A chelating resin functionalized with a specific ligand was used for the selective retention of inorganic mercury.
• Organomercury was determined indirectly by subtracting inorganic mercury from total mercury, with inorganic mercury eluted using thiourea and cold vapor generated using sodium tetrahydroborate.

Main Results:

• The system achieved low detection limits: 10 ng l⁻¹ for CV-AAS and 6 ng l⁻¹ for CV-ETAAS.
• High precision was demonstrated with a 3.5% relative standard deviation (R.S.D.) at 1 µg l⁻¹ Hg level.
• Validation using certified reference materials and spiking experiments confirmed the method's accuracy in determining methylmercury in seafood.

Conclusions:

• The developed on-line FI-CV-AAS/ETAAS system offers a simple and effective approach for mercury speciation in seafood.
• The method accurately differentiates and quantifies inorganic and organomercury (methylmercury) species.
• This technique provides valuable speciation data crucial for environmental monitoring and food safety assessments.