Determination of Organic and Inorganic Mercury Species as Emetine Dithiocarbamate Complexes by High-Performance Liquid Chromatography with Electrogenerated Tris(2,2′-bipyridine)ruthenium(III) Chemiluminescence Detection

Abstract

A sensitive method for simultaneous determination of organic and inorganic mercury species has been developed and is presented in this study. The method is based on complex formation of mercury species with the emetine dithiocarbamate (emetine-CS₂) ligand, HPLC separation, and tris(2,2′-bipyridine)ruthenium(III) chemiluminescence detection. The complexation reactions of the mercury species and emetine-CS₂ ligand occurred instantaneously upon the addition of emetine-CS₂ solution to the solution containing the mercury species. The complete separation of these complexes was achieved using an ODS column with 20 mM NaH₂PO₄-acetonitrile (52:48, v/v) containing 30 mM NaClO₄ as an ion-pair reagent. The calibration graphs of these complexes were linear in the range from 1–100 µg/L. The detection limits were 0.27 µg/L, 0.33 µg/L, 0.39 µg/L, and 0.17 µg/L for methylmercury, ethylmercury, phenylmercury, and the mercury ion, respectively, at a signal-to-noise ratio of 3. The developed technique was validated by analyzing certified reference materials, CRM7402-a (cod fish, NMIJ) and CE464 (tuna fish, ERM), in combination with sonication-assisted acid leaching and liquid-liquid extraction. The emetine-CS₂ ligand has been used for extraction, separation, and detection of mercury species. The results determined using the proposed method were in good agreement with the values of the certified reference materials. The MeHg⁺ and EtHg⁺ recoveries for the spiked samples were found to be almost 100%.

Keywords:

• Chemiluminescence
• HPLC
• Mercury
• Methylmercury
• Tris(2,2′-bipyridine)ruthenium(III)

Acknowledgments

This work was supported by Grants-in-Aid for Scientific Research (No. 18404001 and No. 22404002) from the Japan Society for the Promotion of Science.

Notes

^a Results expressed as the average value of four determinations ± standard deviation.

^b Recovery = (the amount found in the spiked sample – the amount found in the sample) × 100/the amount added.

^c 20 ng (as Hg) of MeHg⁺and EtHg⁺ spiked in the sample, respectively.

^d 100 ng (as Hg) of MeHg⁺and EtHg⁺ spiked in the sample, respectively.