USGS: TWRI BK 9 CH A5.6.4.B: Low-level Mercury in Water Sample Processing
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Official Method Name
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Section 5.6.4.B: Low-level Mercury (of USGS National Field Manual for the Collection of Water-Quality Data) |
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Current Revision
| Version 1.0, October 2004 |
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Media
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WATER |
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Instrumentation
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Filtration Equipment, specific |
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Method Subcategory
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Organic+Inorganic |
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Method Source
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Citation
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Protocol
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TWRI Book 9, Ch. A5 - National Field Manual for the Collection of Water-Quality Data: USGS Techniques of Water-Resources Investigations Book 9, Ch. A5: Processing of Water Samples. |
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Brief Method Summary
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This section of the USGS National Field Manual for the Collection of Water-Quality Data describes the collection, processing, preservation, storage, and shipment of water samples to be analyzed for low-level mercury. Collecting and processing water samples for analysis of mercury at a low (subnanogram per liter) level requires use of ultratrace-level techniques for equipment cleaning, sample collection, and sample processing. These methods are explained. |
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Scope and Application
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This method pertains to Chapter A5: "Processing of Water Samples" from the USGS National Field Manual for the Collection of Water-Quality Data (TWRI Book 9). |
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Applicable Concentration Range
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Interferences
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Low-level mercury samples are susceptible to contamination from many sources, including improperly cleaned equipment; improper sample-collection techniques that allow dust, dirt, or metallic surfaces to contact samples; contaminated preservatives; atmospheric inputs from dust, dirt and rain; and the breath of field personnel having dental amalgam fillings, if the breath contacts the sample. |
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Quality Control Requirements
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Established techniques and associated quality-assurance (QA) procedures for the collection and processing of water samples for trace-element analysis at the part-per-billion level (NFM 3–5) are not adequate for low-level mercury samples. Modifications to the part-per-billion procedures are necessary to minimize contamination of samples at a typical ambient mercury concentration, which commonly is at the subnanogram-per-liter level. |
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Sample Handling
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Do not store or ship samples on ice. Do not expose samples to light or heat. |
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Maximum Holding Time
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Samples must be shipped within 14 days of collection. |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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Method contains very specific steps that must be taken for collection and processing. Acid treatment must be added to the samples within 24 hours of filtration. |
