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To: Members, Affiliates & Water Quality Committee
From: National Office
Date: June 8, 1998
Re: RA 98-10

Proposed Mercury Method

In the May 26, 1998 Federal Register, EPA published a proposed new analytical method for mercury, EPA Method 1631; Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence. Method 1631 measures mercury by purging mercury vapor from a water sample onto a gold trap and thermally desorbing the mercury from the trap into an atomic fluorescence spectrometer. Purging the mercury onto the gold trap concentrates the mercury and allows water vapor from the sample to be vented, and use of atomic fluorescence provides an increased response compared to atomic absorption. As a result, EPA Method 1631 is approximately 200 times more sensitive than currently approved methods for determination of mercury. Method 1631 would need to be used in conjunction with clean sampling and laboratory techniques to preclude contamination at the low ppt levels necessary for mercury determinations. EPA has developed guidance documents on sampling and clean rooms for trace metals, including mercury.

AMSA's Water Quality Committee is leading a review of the proposed analytical method for mercury. If you have specific concerns or would like to comment on the proposal, please provide your comments to AMSA's National Office by July 9, 1998. The Water Quality Committee will be reviewing comments from the membership during its July 14 meeting in Colorado Springs. If you have questions, please call Mark Hoeke, AMSA 202/833-9106 or mhoeke@amsa-cleanwater.org.

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