Performance Evaluation of an Improved GC-MS Method to Quantify Methylmercury in Fish

Area of Science:

• Environmental Chemistry
• Analytical Chemistry

Background:

• Methylmercury is a neurotoxicant found in fish, necessitating accurate analytical methods for regulatory compliance.
• Previous methods for methylmercury analysis using phenyl derivatization and gas chromatography-mass spectrometry (GC-MS) had limitations.

Purpose of the Study:

• To improve the existing methylmercury analytical method for enhanced accuracy and efficiency.
• To validate the improved method for determining methylmercury levels in fish according to food safety regulations.

Main Methods:

• Modified phenylation of methylmercury using sodium tetraphenylborate in a toluene/water two-phase system.
• Suppressed adsorption of methyl phenyl mercury in the GC system via co-injection of PEG200.
• Validation using certified reference materials and methylmercury-spiked fresh fish samples by three independent analysts.

Main Results:

• The two-phase system enabled derivatization at optimum pH, significantly reducing by-product formation.
• Co-injection of PEG200 prevented adsorption in the GC system, allowing continuous analysis without sensitivity loss.
• Independent validation confirmed the method's suitability for regulatory compliance.

Conclusions:

• The enhanced analytical method provides a more accurate and sensitive determination of methylmercury in fish.
• This improved method is suitable for assessing compliance with provisional methylmercury regulation values in food safety.
• The modifications represent a significant advancement in methylmercury analysis for environmental and food safety monitoring.