1. Mercury Collection and Analysis in Ambient and Effluent Waters using EPA Method Overview of Sampling and Analysis William Telliard U.S. EPA Office of Science and Technology

2. Contamination Control Philosophy
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
Sample bottles
Sampling equipment
Reagents
Laboratory environment
Laboratory glassware and equipment

3. Equipment Cleaning Preclean
All equipment and containers must be non-metallic
Clean all sampling equipment and containers using detergent, mineral acids, and reagent water as described in Method 1669
Verify cleanliness
Generate acceptable equipment blanks
Demonstrates equipment and containers are free from contamination
Storage
Fill cleaned sample containers with 0.1% (v/v) ultrapure HCl and individually double-bag
Bag or wrap all sampling equipment for storage and shipment

4. Sample Collection Using Method 1669
“Clean Hands/Dirty Hands”
A two-person sampling team is required
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

5. Sample Collection Using Method 1669
The presence of potential sources of contamination is of extreme importance in site selection
To minimize contamination—
Collect samples facing upstream and upwind
Avoid collecting samples during precipitation events
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

6. Sample Collection Using Method 1669 (cont.)
Method includes procedures for collection of samples for determination of total recoverable metals and dissolved metals
Sample Filtration
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
Conducted in the field or in the laboratory
Field preservation must be performed in a glove bag or a designated clean area

7. Quality Assurance/Quality Control
Equipment Blanks
Bottle blanks
Sampler Check Blanks
Field Blanks
Must be collected to assess the likelihood of contamination in the samples.
Field blanks are collected before samples
Field Duplicates
Collected to assess precision of the sampling and analytical processes

8. Blanks and Definitions
Equipment Blank
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

9. 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
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

10. Laboratory Analysis using Method 1631
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 ng/L
The ease of contamination samples cannot be overemphasized
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

11. Laboratory Analysis using Method 1631 (cont.)
A 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

12. Laboratory Analysis using Method 1631 (cont.)
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.

13. Figure 1. Cold Vapor Atomic Fluorescence Spectrometer (CVAFS) System (Method 1631)

14. Figure 2. Automated Mercury Fluorescence System (Method 245.7)

15. Clean Spaces Guidance
Draft guidance on the establishment of trace metal clean rooms in existing facilities was completed in April 1995, with minor revisions in January The guidance includes:
A general design of a trace metals clean laboratory;
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.

16. Clean Spaces Guidance (cont.)
Basic requirements
metal free work surfaces and hoods
positive pressure with HEPA-filtered air
clean water
Achieved with commercially available materials
Installed into existing facilities
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

17. Analysis Tips
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