Mercury Collection and Analysis in
Ambient and Effluent Waters using
EPA Method 1631
Overview of Sampling and Analysis
William Telliard
U.S. EPA Office of Science and Technology
Office of Water
Mercury workshop- sampling.ppt
Contamination Control Philosophy
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Ensure any object or substance that contacts the samples is
nonmetallic and free from any material that may contain metals
of concern
Mercury must be eliminated or reduced to a level that will not
compromise the measurement
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Sample bottles
Sampling equipment
Reagents
Laboratory environment
Laboratory glassware and equipment
Office of Water
Mercury workshop- sampling.ppt
Equipment Cleaning
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Preclean
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All equipment and containers must be non-metallic
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Clean all sampling equipment and containers using detergent,
mineral acids, and reagent water as described in Method 1669
Verify cleanliness
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Generate acceptable equipment blanks
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Demonstrates equipment and containers are free from
contamination
Storage
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Fill cleaned sample containers with 0.1% (v/v) ultrapure HCl and
individually double-bag
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Bag or wrap all sampling equipment for storage and shipment
Office of Water
Mercury workshop- sampling.ppt
Sample Collection Using Method 1669
“Clean Hands/Dirty Hands”
 A two-person sampling team is required
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One person is designated “Clean Hands” and performs all
operations involving direct contact with the sample and bottles
The other person is designated “Dirty Hands” and is responsible for
operation of machinery and activities not involving direct contact
with the sample
Sampling personnel must wear clean, non-talc gloves, and may
need to wear other clothing, such as disposable coveralls or nylon
windsuits, caps, and shoulder-length glove liners, to prevent
sample contamination
Office of Water
Mercury workshop- sampling.ppt
Sample Collection Using Method 1669
The presence of potential sources of contamination is of extreme
importance in site selection
 To minimize contamination—
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Collect samples facing upstream and upwind
Avoid collecting samples during precipitation events
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During a 9 POTW Great Lakes study, the Hg field blank collected on
the only rainy day had a Hg concentration 3 times higher than any
other field blank in the study
Collect samples as far as possible from metal supports, bridges,
wires, and heavily traveled roads
Office of Water
Mercury workshop- sampling.ppt
Sample Collection Using Method 1669 (cont.)
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Method includes procedures for collection of samples for
determination of total recoverable metals and dissolved metals
Sample Filtration
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For dissolved metals, samples are filtered through a 0.45-um
capsule filter at the field site
A continuous-flow sampling system with an in-line filter can simplify
sample collection and filtration
Sample Preservation
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Conducted in the field or in the laboratory
Field preservation must be performed in a glove bag or a
designated clean area
Office of Water
Mercury workshop- sampling.ppt
Quality Assurance/Quality Control
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Equipment Blanks
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Field Blanks
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Bottle blanks
Sampler Check Blanks
Must be collected to assess the likelihood of contamination in the
samples.
Field blanks are collected before samples
Field Duplicates
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Collected to assess precision of the sampling and analytical
processes
Office of Water
Mercury workshop- sampling.ppt
Blanks and Definitions
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Equipment Blank
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Bottle Blank - generated by filling a sample bottle with reagent
water acidified to pH < 2, allowing the bottle to stand for 24 hours,
and analyzing the water
Sampler Check Blank - generated at the lab by processing reagent
water through the sampling equipment using the same procedures
that will be used in the field, and collecting and analyzing the water
Field Blank - generated by filling a large carboy with reagent
water in the laboratory, transporting the container to the field,
processing the reagent water through the entire sampling
equipment system, and analyzing the sample
Office of Water
Mercury workshop- sampling.ppt
Summary
Rigorous sample handling procedures are necessary to ensure
samples are not contaminated
 Stringent QC is necessary to ensure the validity of the analytical
results
 Not all of the procedures described in Method 1669 may be
necessary for effluent sampling
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Level of protection required depends on sampling environment,
monitoring levels of interest, and metals of interest
The low levels of Hg (<36 ng/L) found in a 9 POTW Great Lakes
Study suggests these clean techniques may be required for some
metals
Office of Water
Mercury workshop- sampling.ppt
Laboratory Analysis using Method 1631
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For determination of mercury in filtered and unfiltered water by
oxidation, purge and trap, desorption, and cold-vapor atomic
fluorescence spectrometry (CVAFS)
Method detection limit is 0.2 ng/L and the range is 0.5 - 100 ng/L
The ease of contamination samples cannot be overemphasized
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Method includes suggestions for improvements in facilities and
analytical techniques that minimize contamination and maximize
the ability of the laboratory to make reliable trace metals
determinations
Performance-based
Accompanied by Method 1669
Office of Water
Mercury workshop- sampling.ppt
Laboratory Analysis using Method 1631 (cont.)
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A 100-2000 mL sample is collected directly into a specially
cleaned, pretested, fluoropolymer bottle using appropriate
sample handling techniques
For dissolved mercury, the sample is filtered through a 0.45 uM
capsule filter
The sample is preserved by adding 5mL/L of pretested HCl or 5
mL/L BrCl solution.
BrCl solution is added to oxidize all Hg compounds to Hg(II)
The sample is pre-reduced with NH2OH-HCl to destroy the free
halogens
Office of Water
Mercury workshop- sampling.ppt
Laboratory Analysis using Method 1631 (cont.)
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The sample is then reduced with SnCl to convert Hg(II) to volatile
Hg(0).
The Hg(0) is separated from solution by purging with nitrogen
onto a gold-coated sand trap
The trapped Hg is thermally desorbed from the gold trap into an
inert gas stream that carries the released Hg(0) into the cell of a
CVAFS for detection
Quality is assured through calibration and testing of the
oxidation, purging, and detection systems.
Office of Water
Mercury workshop- sampling.ppt
Figure 1. Cold Vapor Atomic Fluorescence
Spectrometer (CVAFS) System (Method 1631)
Office of Water
Mercury workshop- sampling.ppt
Figure 2. Automated Mercury Fluorescence
System (Method 245.7)
Office of Water
Mercury workshop- sampling.ppt
Clean Spaces Guidance
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Draft guidance on the establishment of trace metal clean rooms
in existing facilities was completed in April 1995, with minor
revisions in January 1996. The guidance includes:
A general design of a trace metals clean laboratory;
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Delineation of the hierarchy of cleanliness needed within the
laboratory, including change rooms;
Description of HEPA-filtered air and clean water supplies, which are
essential in a trace metals laboratory; and
Detailed descriptions of materials and modifications used to
construct a trace metals clean room in an existing laboratory.
Office of Water
Mercury workshop- sampling.ppt
Clean Spaces Guidance (cont.)
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Basic requirements
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metal free work surfaces and hoods
positive pressure with HEPA-filtered air
clean water
Achieved with commercially available materials
Installed into existing facilities
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Paint the walls with metal-free paint (epoxy- or latex-based) to
which has been added a small amount of sulfur powder to react
with mercury that could diffuse out of the underlying surfaces
All metal fixtures and appliances should be replaced with non-metal
counterparts
Office of Water
Mercury workshop- sampling.ppt
Analysis Tips
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Clean all work surfaces in which samples will be processed
Reagent water should be monitored for Hg
Samples known to contain high levels of mercury (greater than
100 ng/L) should be diluted prior to bringing them into the clean
room or area
Sample processing and analysis should occur as far as possible
from sources of airborne contamination
Effluent from the CVAFS should pass through either a column of
activated charcoal or a trap containing gold or sulfur to
amalgamate or react mercury vapors
Office of Water
Mercury workshop- sampling.ppt