Method 1631: Measurement of Mercury in Water
This method allows for the determination of mercury at a minimum level of 0.5 parts-per-trillion and supports measurements for mercury published in the National Toxics Rule and in the Final Water Quality Guidance for the Great Lakes System. Includes Guidance for Implementation and Use of Method 1631 and Revision E to the method, which contain additional and revised requirements.
Revision E, Final Rule
This final rule replaces the currently approved version of Method 1631 and includes revisions that address stakeholder concerns. This revision clarifies quality control and sample handling requirements and allows flexibility to incorporate additional available technologies. This rule also amends the requirements regarding preservation, storage, and holding time for low level mercury samples.
This method replaces the previously approved Method 1631 Revision C.
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- Analytical Methods for Mercury in NPDES Permits (PDF) (4 pp, 68K)
This memo describes when a method for mercury is "sufficiently sensitive" for purposes of permit applications and monitoring under a permit. The memo also provides information on EPA's March 12, 2007, approval of Method 245.7 for measurement of mercury and modified versions of approved analytical methods for mercury as well as the impact of their approval on the NPDES permitting process.
- Method 245.7 Mercury in Water by Cold Vapor Atomic Fluorescence Spectrometry (PDF) (33 pp, 195K)
- Method 1631, Revision E: Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Sepctometry (PDF) (46 pp, 1.5MB)
- Fact Sheet for the Final Rule (October 2002)
- Federal Register Notice announcing final rule (October 29, 2002)
Note: EPA no longer updates this information, but it may be useful as a reference or resource.