Flett Research Ltd
440 DeSalaberry Avenue, Winnipeg MB CANADA Phone/Fax: (204) 667-2505
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Flett Research - Mercury Sampling Information

Collecting samples for ultra-trace level mercury or methyl mercury analysis requires special precautions and procedures. Our staff can give advice on sampling techniques and correct selection of supplies.

Some information is provided below but we highly recommend you contact the laboratory so that we can determine the specifics of your project. This will help us determine the appropriate sampling instructions and choice of bottles/supplies for your specific needs. Details like the depth(s) at which you are sampling, whether you will be dip sampling or using a pump, if you will be anchored or drifting, etc. are all important and will change our instructions for sampling.

A table of recommended holding times for mercury samples can be found here and information on Flett quantitation limits and pricing can be found here .

Sample Submission and Shipping

Please try to ship samples on either a Monday, Tuesday or Wednesday, as this will ensure that they do not get held up by a courier over a weekend and risk sample degradation. When using freezer packs in shipments 'blue ice' is always preferred to water ice.

Water samples:

Our sampling protocol for the collection of water samples utilizes acid cleaned Teflon or glass bottles and clean room gloves. PETG bottles may also be used for methyl mercury samples. We can give advice on the correct selection of bottles and may be able to supply limited numbers of precleaned Teflon bottles, or larger numbers of precleaned glass bottles.

We require 125mL of sample for total mercury analysis and 200mL (250mL bottle filled no more than 80-85% full) of sample for methyl mercury analysis.

The cost of supplying water bottles is included in the analytical cost; shipping costs will be added to your invoice or can be charged to your own courier account.

DI water for rinsing and travel blanks is available at $10.00/2.5 L bottle. Gloves can be supplied to our clients at a cost of $ 2.00 per sampling location (assuming that there are 2 persons on a field crew involved in sample collection using clean hands-dirty hands technique).

Total Hg water samples are stable in darkness for 28 days without preservation or refrigeration. Do not freeze total mercury samples because there is some evidence that Hg+2 converts to Hg0 during freezing and there is a loss of this volatile form of Hg upon thawing the sample.

If water samples for methyl Hg analysis cannot be shipped to us cold within 48 hours, then they should be frozen or preserved with low Hg HCl (pre-analyzed and supplied by Flett Research) to 0.2% . Salt water samples are acid preserved with H2SO4 to a final concentration of 0.2 %. The HCl or H2SO4 is supplied at a cost of $50.00. Do not fill Teflon bottles more than 80-85% or they may break when frozen. If 250 mL glass is used for methyl mercury samples and they are to be frozen, then they must not be filled more than 60% full and should be frozen while on their sides in order to avoid breakage due to expending ice. The holding time for frozen samples is 180 days.

When ready to ship, remove the methyl Hg samples from the freezer and place them in an upright position in a cooler. If they are glass bottles, insert them in bubble wrap pouches to protect them against breakage due to rough handling during transport. Use additional soft padding to keep the ice packs from contacting and possibly breaking the bottles. There should be no empty space in the cooler when it is ready to ship. Add freezer packs (or dry ice if necessary, but not regular water ice) to keep samples frozen.

The total Hg samples are similarly protected and placed in a cooler. This should be a separate cooler from the methyl samples. During warm weather the cooler can be submitted without ice packs but, when shipping in freezing weather room temperature ice packs should be included with the samples.

Both coolers should be well taped to prevent opening and to exclude dust.

Sediment/Soil samples:

Unsaturated sediment/soil samples may be placed into 250 mL, tightly sealing, precleaned, polyethylene widemouth jars or in new ZipLoc bags (double). Do not fill jars more than 2/3 full.

Recommended holding time for frozen (~ -20oC) sediment is 180 days; at 1-6oC the holding time is 28 days.

Make certain the caps are tightly closed and that no sediment covers the sealing surfaces of the jar before closing. Sediment jars should be filled no more than 2/3 full and then frozen. If jars are too full they may break due to expanding ice. Label the cap and the jar body. We recommend the use of permanent inks for labeling as paper labels may have trouble staying adhered to the frozen jars.

Make sure the jars are upright and well padded against breakage during transport. Ship to the lab in a cooler on blue ice if overnight delivery is certain. If delivery could be longer, send on an appropriate weight of dry ice in a well insulated cooler.

Tissue samples:

Recommended holding time for frozen (~ -20oC) fish tissue is 180 days; tissue which has been freeze-dried can be stored indefinitely.

Tissue can be stored in new ZipLoc bags (double) or a Whirl Pac bag. From larger fish remove about 2-10 g of fillet from the fish and package. For fish smaller than 10 cm in length, send the entire fish in similar packaging.

Tissue samples should be frozen and shipped on dry ice if possible. Overnight shipment on blue ice is also acceptable but risky because of possible transport delays. Keep dry ice from directly contacting bags as it can cause the bags to become brittle and crack.

Tissue biopsy samples:

Flett Research participated in a study which has demonstrated the accurate measurement of Hg in small tissue biopsies (< 50 mg) thus permitting live fish to be non-lethally sampled and returned in good health to the water. This technique will be of interest to agencies that are responsible for continuous monitoring of mercury concentrations in fish populations. Baker et al. 2004, Evaluation of Non-lethal Methods for the Analysis of Mercury in Fish Tissue, Transactions of the American Fisheries Society, 133:568-576.

Extra care must be taken with tissue biopsies to eliminate errors associated with small samples.

The sample is best placed in a 2 ml Cryovial (which experience has shown to be free of Hg contamination and leak proof) immediately after sampling and tightly capped. It is important that the introduction of extra water be avoided during sampling because the extra water will cause the apparent % loss on drying to be artificially elevated. It is equally important that the vials are tightly closed so that moisture is not lost during frozen storage of the samples.

Use permanent inks for labeling (test for durability) and avoid use of paper labels because they will make it difficult to obtain accurate weights of the vials at the laboratory. The vials should be kept on ice until they can be frozen for long term storage. Samples can be sent to the lab in a cooler on blue ice if overnight delivery is certain. If delivery could be longer, send on an appropriate weight of dry ice in a well insulated cooler.

If these small tissue samples are sealed tightly and frozen as soon as possible after sampling, as instructed above, holding time is 180 days but we prefer to receive these small samples at the laboratory as soon as possible so that they can be freeze-dried. This helps to eliminate errors associated with loss of moisture which can be an issue with very small tissue samples. Once freeze-dried the samples have an indefinite holding time.

Shipping with Dry Ice

Check requirements with your shipping provider but most courier companies accept shipments with limited quantities of dry ice without Dangerous Goods declaration when shipping dry ice together with a non-Dangerous Good.

Follow the link to dryicesource.com for guidelines on safe handling of dry ice.

The waybill and outside of the package must be marked with the names and addresses of both you and the consignee. You may write the information directly on the box or affix a label with the required information to the box.

As a general guideline the following amounts of dry ice should be sufficient for a 2 day shipping time:

1 kg sample/5kg dry ice
5kg sample/10 kg dry ice

Terms of Engagement

In order to maintain our professional liability insurance coverage (which many clients demand), our insurer requires us to have either a detailed purchase order or a signed "Terms of Engagement" document for every client. If a purchase order with contractual obligations will not be issued by your organization, please read and then sign our " Terms of Engagement " document. It can be returned by postal mail, fax, or as a pdf via email.

For additional information, contact Dr. Robert Flett at flett@flettresearch.ca

Return to the Flett Research Mercury Page.

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Flett Research Ltd - 440 DeSalaberry Ave - Winnipeg Manitoba CANADA R2L 0Y7

Phone/Fax: (204) 667-2505