Determination of Hg in Sediment

Jody had a number of solutions that were extracted from small river sediment samples (<50mg) using a sequential digestion. The extracts had been preserved in 0.5% BrCl or 5% Aqua Regia + 0.01% potassium dichromate in order to preserve Hg for analysis by atomic fluorescence. She wanted to try to determine the concentrations of other trace elements (particularly the Lanthanides) by ICP-MS. Jody wondered if her proposed preparation method (see below) would work and whether Paul could offer some additional advice.

	RE: Determination of Hg in Sediment Dear Jody,      HDPE is not stable to strong oxidizers like Aqua Regia and BrCl. I would suggest using PFA or PTFE Teflon containers. In addition, these containers can be heated for your evaporation. Be sure to acid leach the containers with nitric acid before using, since new Teflon is not as clean as polyethylene.      Regarding your planned method: "I plan to evaporate the samples and make them up in 1% nitric in order to minimize the bromide and chloride interferences."      I believe this method of evaporating your samples and making them up in dilute nitric acid will work for you. You may want to add some concentrated nitric acid before evaporation. Please feel free to contact me with any questions or comments.     Paul R. Gaines, Ph.D. Serving you in chemistry