Frequently Asked Questions - Stabilizing mercury (Hg) with gold (Au)

I am writing to get your input on the role of gold towards the stabilization of mercury. In the following link and subsequent EPA report it states that gold acts as a stabilizer for mercury. Can you please suggest if there are any ratios (either atomic or %) between Hg and Au to achieve maximum stability without the addition of too much Au? Our range of Hg measurement is 0.05-20 ppb (ng/mL) for samples subjected to a 250 deg C microwave digestion at 40 bar pressure. Thank you, Looking forward to hearing from you.
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We have limited data regarding the use of Au to stabilize Hg at ‘low’ concentrations, but we have studied 10, 50, and 100 ppb solutions of Hg in a matrix of 2% (v/v) HNO3 with 1 ppm of Au (as AuCl3) added as a stabilizer. These three Hg solutions were stored in acid-leached LDPE bottles, and for each solution Hg was stable for at least 3 years. Based upon these data, and considering your expected Hg concentrations of 20 ppb, we believe that a 1 ppm Au spike should be sufficient to stabilize Hg if the matrix is HNO3 and the preparation/storage containers are clean polyethylene. What we do not know is how your microwave digestion method may affect Hg stability, or if Au would be a suitable option for stabilization as part of the digestion process. If you could provide details of the digestion method (sample type, acids used, etc.) we may be able to offer additional suggestions or information.

Posted: 08/30/18 21:04:35

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