Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry. Designed for ultra-trace mercury detection at parts-per-trillion levels.
EPA 1631E requires fluoropolymer or borosilicate-glass bottles pre-cleaned to the method's protocol. Samples are preserved with 0.5% BrCl or 0.5% HCl on collection.
Avoid contact with any source of mercury (powdered gloves, ungloved hands, lab air).
Oxidize all mercury species to Hg(II) with BrCl, then pre-reduce excess oxidant with NH₂OH·HCl.
Reduce Hg(II) to Hg(0) with SnCl₂ and purge onto a gold trap.
Thermal desorption of the gold trap delivers Hg(0) to a CVAFS detector for quantitation.
The EPA method requires:
