A methodological study of mercury speciation using dogfish liver CRM (DOLT-2)

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Biochemistry

Background:

• Mercury (Hg) speciation is vital for understanding its toxicological effects and biological interactions.
• Selenium (Se) is known to have protective mechanisms against mercury toxicity.
• Accurate analytical methods are needed to differentiate mercury species in biological matrices.

Purpose of the Study:

• To optimize analytical methods for mercury chemical speciation.
• To investigate the role of selenium in mercury's protective mechanisms.
• To validate methods using certified reference material DOLT-2 (Dogfish liver).

Main Methods:

• Sample preparation involved homogenization, ultracentrifugation, and size exclusion chromatography (Sephadex G-75).
• Mercury species (total Hg, methylmercury (MeHg), inorganic mercury (Hg2+)) and selenium (Se) were quantified.
• Gas chromatography with cold vapour atomic fluorescence spectrometry (GC-CVAFS) and cold vapour atomic absorption spectrometry (CVAAS) were employed.

Main Results:

• Optimized methods were developed for determining mercury species in whole tissue, soluble, and insoluble fractions.
• Simultaneous determination of MeHg and Hg2+ via alkaline dissolution followed by GC-CVAFS is recommended for soluble fractions.
• Solvent extraction for MeHg and acid digestion CVAAS for total Hg are recommended for insoluble fractions.

Conclusions:

• The optimized analytical methods provide accurate speciation of mercury in dogfish liver.
• These methods will aid in studying the protective role of selenium against mercury toxicity.
• Specific methods are recommended based on sample matrix and mercury concentration.