Simultaneous combustion preparation for mercury isotope analysis and detection of total mercury using a direct mercury analyzer

Maxime Enrico; Prentiss Balcom; David T Johnston; Julien Foriel; Elsie M Sunderland

doi:10.1016/j.aca.2021.338327

Simultaneous combustion preparation for mercury isotope analysis and detection of total mercury using a direct mercury analyzer

Anal Chim Acta. 2021 Apr 15:1154:338327. doi: 10.1016/j.aca.2021.338327. Epub 2021 Feb 17.

Authors

Maxime Enrico¹, Prentiss Balcom², David T Johnston³, Julien Foriel³, Elsie M Sunderland⁴

Affiliations

¹ Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA. Electronic address: menrico@seas.harvard.edu.
² Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA.
³ Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St, Cambridge, MA, 02138, USA.
⁴ Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard University, 29 Oxford St, Cambridge, MA, 02138, USA; Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St, Cambridge, MA, 02138, USA.

PMID: 33736793
DOI: 10.1016/j.aca.2021.338327

Abstract

Mercury (Hg) stable isotope signatures are widely used to understand Hg cycling in the environment. Sample preparation methods for determining Hg isotope ratios by CV-MC-ICP-MS vary widely among laboratory facilities and sample types. Here, we present a novel and rapid method for preparing solid samples prior to determining Hg isotope composition. We use a direct Hg analyzer (that measures total Hg) for sample combustion, amalgamation and analysis. During the thermal release of Hg from the amalgamator and following detection, the analyte gas enters a trapping solution consisting of 10% HCl/BrCl (5:1, vol/vol). We find Hg blank values are less than 1% of the Hg introduced during sample analysis, Hg detection is not altered by modifying the system, and more than 90% of the introduced Hg is recovered in the trapping solution. Hg isotope results are statistically indistinguishable from accepted values for previously published certified reference materials and uncertainty of 2σ (0.05-0.12‰) is similar to the solution standard RM8610 (2σ = 0.09‰). This new method allows for solid sample preparation for Hg isotope analysis in under 15 min. It has the additional advantage of minimizing use of sample mass during simultaneous detection and preparation.

Keywords: Combustion; Inductively coupled plasma mass spectrometry; Pre-concentration; mercury isotopes.