Particulate total mercury Brooks-Rand "MERX"

Analysis of Methylmercury in Water by Distillation, Gas Chromatography Separation, and Speciated Isotope Dilution Mass Spectrometry.

The following standard operating procedure (SOP) is used by the U.S. Geological Survey’s Mercury Research Laboratory (MRL) to determine total mercury (HgT) concentrations in suspended particulate matter. This SOP describes the preparation of the sample and subsequent analysis. Particulate matter is captured on baked (550°C for two hours) quartz fiber filters and stored frozen on Teflon petri dishes. The filters are extracted in a 5% Bromine Monochloride (BrCl) solution at 50°C for five days in Teflon bottles to release matrix-bound mercury and oxidize all forms of mercury to the Hg2+ oxidation state. Immediately prior to analysis, the BrCl is neutralized by the addition of Hydroxylamine Hydrochloride (NH2OH*HCl). Following neutralization, Stannous Chloride (SnCl2) is added to the sample to reduce the mercury from Hg2+ to Hg0 . The volatile Hg0 is purged from the sample and captured on a gold sand trap, desorbed, and detected by cold vapor atomic fluorescence spectrometry (CVAFS). Sample analysis is conducted by the Brooks-Rand “MERX” automated mercury analytical system. Quality assurance and control protocols are employed throughout sample preparation and analysis, including: laboratory practices to prevent sample contamination, method and analytical blanks, analytical replication, analytical matrix spikes, and analysis of certified reference material (CRM).

Mercury Research Laboratory, 2016