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

• Published in: Analytica chimica acta Vol. 1054; pp. 95 - 103
• Main Authors: Janssen, S.E., Lepak, R.F., Tate, M.T., Ogorek, J.M., DeWild, J.F., Babiarz, C.L., Hurley, J.P., Krabbenhoft, D.P.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.04.2019; Elsevier BV
• Subjects: Bromine; Customization; Desorption; Gold; Inductively coupled plasma mass spectrometry; Mercury; Mercury (metal); Mercury isotopes; Organic chemistry; Pre-concentration; Sediments; Stable isotopes; Trapping; Desorption; Inductively coupled plasma mass spectrometry; Pre-concentration; Mercury isotopes
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2018.12.026

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% 3HNO3: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. [Display omitted] •Desorption method to triple throughput and expand applicability of Hg isotope measurements.•Comparison of different oxidants for collection of gaseous elemental Hg.•Measurement precision of ±0.11‰ (2SD, n = 42) for δ202Hg in 40 min preparation in a 2 mL trapping volume.