Preconcentration, Speciation, and Determination of Mercury by Solid Phase Extraction with Cold Vapor Atomic Absorption Spectrometry

Abstract

In this study, inorganic mercury [iHg (Hg²⁺)] and monomethylmercury [MeHg (CH₃Hg⁺)] ions have been preconcentrated and determined by a column solid phase extraction method. Cold vapor atomic absorption spectrometry was used for the determination of mercury species. Optimum retention and elution parameters were determined for both mercury species separately. For this purpose, the effect of pH, flow rate and volume of sample solution, type, and concentration of eluent on the recovery of mercury species were investigated. Effects of possible interfering ions were also studied. Optimum values of flow rate, pH, and volume of sample solution were found to be 3 mL min⁻¹, 4.0 and 50 mL, respectively, for both iHg and MeHg ions. Although the both species were retained at pH 4, the elution could be performed only with different eluents. While MeHg ions were eluted with 10 mL of 0.1 mol/L HCl solution, iHg ions were eluted with 10 mL of 0.2 mol L⁻¹ thioureasolution in 3 mol L⁻¹HCl. Limits of detection for iHg and MeHg were 0.44 µg L⁻¹ and 0.56 µg L⁻¹, respectively. To validate the proposed speciation and/or preconcentration method, a certified reference material (ERM-CE464) was analyzed and MeHg was determined with a relative error of 7.3%. The accuracy was also checked by analyzing spiked water and fish samples for both species.

Keywords:

• Cold vapor atomic absorption spectrometry
• Mercury
• Methyl mercury
• Solid phase extraction
• Speciation

Acknowledgments

The authors are grateful for the financial support of Gazi University Scientific Research Projects Unit (Project No. 05/2011-30).

Notes

^a Mean of three replicates ± standard deviation; N.D.: Not detected.

^a Mean of three replicates ± standard deviation.

^a Mean ± standard deviation (N = 3).

^b Total Hg = iHg + MeHg (as Hg).

^a PF, Preconcentration factor.

^b AC, Adsorption capacity.

ICP-OES, Inductively coupled plasma optical emission spectrometry; CVAAS, Cold vapor atomic absorptionspectrometry; LOD, Limit of detection.