Rapid pre-concentration of mercury in solids and water for isotopic analysis.

Journal: Analytica chimica acta
Published Date: Dec 21, 2018

Abstract

The precise quantification of mercury (Hg) stable isotope compositions in low concentration or dilute samples poses analytical challenges due to Hg mass limitations. Common Hg pre-concentration procedures require extended processing times, making rapid Hg stable isotope measurements challenging. Here we present a modified pre-concentration method that combines commonly used Hg reduction and gold trap amalgamation followed by semi-rapid thermal desorption (less than 1 h) and chemical trapping. This custom designed system was demonstrated to perform adequately on multiple trapping matrices including a new bromine monochloride (BrCl) wet oxidant trap (40% 3HNO:BrCl), capable of trapping consistently in 2 mL volume over a wide range of Hg masses (5-200 ng). The procedure was also shown to work effectively on natural matrices, waters and sediments, producing comparable isotope results to the direct digestion analyses. Here, we present a method that can effectively triple sample throughput in comparison to traditional procedures, and also access lower concentration matrices without compromising the accuracy or precision of Hg isotope measurements.

Authors

  • S E Janssen
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA. Electronic address: sjanssen@usgs.gov.
  • R F Lepak
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA; Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI, 53706, USA.
  • M T Tate
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA.
  • J M Ogorek
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA.
  • J F DeWild
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA.
  • C L Babiarz
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA.
  • J P Hurley
    Environmental Chemistry and Technology Program, University of Wisconsin-Madison, Madison, WI, 53706, USA; Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA; University of Wisconsin Aquatic Sciences Center, Madison, WI, 53706, USA.
  • D P Krabbenhoft
    United States Geological Survey, Upper Midwest Water Science Center, Middleton, WI, 53562, USA.

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