A new method for total mercury and methyl mercury analysis in muscle of seawater fish.

In this work we have developed a cost-effective method for the analysis of methyl mercury (MeHg) in seawater fish muscle. The novelty of this method lies in the use of microwave-assisted extraction with acidic solution (HCl), addition of toluene, and subsequent extraction with cysteine acetate solution where only MeHg is present because of its affinity for cysteine groups. MeHg in cysteine phase and total mercury in the homogenate muscle tissue were determined using a direct Hg analyzer (DMA-80). Validation, precision, and accuracy of the method were evaluated and monitored with a tuna fish certified reference material (CRM 463) containing MeHg.