Speciation of mercury in fish oils using liquid chromatography inductively coupled plasma mass spectrometry

This paper describes a simple and rapid procedure, using liquid chromatography (LC) followed by pneumatic nebulization inductively coupled plasma mass spectrometry (ICP-MS), for the separation and determination of inorganic, methyl, and ethyl mercury compounds. We obtained well-resolved chromatograms within 6 min using a reversed-phase C8 column as the stationary phase and a solution containing 0.6% v/v 2-mercaptoethanol and 3% v/v methanol as the mobile phase. We applied this method to the speciation of mercury in several fish oil samples purchased locally. The accuracy of the procedure was verified through the analysis of a reference material (NRCC DOLT-3 Dogfish Liver) certified for both total mercury and methyl mercury. The detection limits of the studied mercury compounds were in the range 0.013-0.026 ng Hg mL(-1) in the injected solutions, corresponding to 0.5-1 ng g(-1) in the original fish oil samples. Employing a microwave-assisted extraction procedure and the mobile phase solution for the extraction of the mercury compounds, we obtained an extraction efficiency of greater than 89% from the fish oil samples. The recoveries of the individual mercury species added to the samples at 10-25 ng Hg g(-1) were between 93 and 107%. The precision measured between sample replicates was greater than 12% for all determinations. (C) 2017 Elsevier B.V. All rights reserved.