Analysis of Total Mercury in Water by Cold Vapor Atomic Fluorescence

Analysis of Total Mercury in Water by Cold Vapor Atomic Fluorescence Detection with the Brooks-Rand “MERX” Automated Mercury Analytical System

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 water. This SOP describes the preparation of the sample and subsequent analysis. Samples are collected into Teflon bottles and preserved to 1% v/v with MRL-supplied Hydrochloric Acid. Bromine Monochloride (BrCl) is added to the sample and heated to 50°C for five days 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 onto 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 blanks, analytical replication, and analytical matrix spikes.

Mercury Research Laboratory, 2016