Sample Collection and Preservation

Please use the following guidelines when preparing samples in the field. Feel free to contact our Project Coordinator, Shanda McGraw at smcgraw@ecoanalysts.com, if you have difficulty finding any of the materials mentioned below.

Sample Containers

16oz jar—a better fit for smaller samples

US Plastic: 16 oz. Clear PET Round Jar with Label Panel & 63/400 White Ribbed Cap with F217 Liner

ULine: Natural Round Wide-Mouth Plastic Jars - 16 oz

32oz Jar—will fit most samples (larger samples may require 2+ containers)

US Plastic: 32 oz. Clear PET Round Jar with Label Panel & 89/400 Neck | Cap sold separately

ULine: Clear PET Round Wide-Mouth Plastic Jars - 32 oz

Labeling

Clear and accurate labels are critical. Use two identical labels per container, one placed inside the container and one attached to the exterior. Use whatever information is appropriate to your needs on the labels, but make sure it clearly defines each sample. Maintain a simple labeling system.

External labels are convenient when organizing samples and provide a safeguard against loss of the internal label. However, exterior labels are subject to much abuse and are often rendered illegible so they should only be used in conjunction with an internal label. Attach the labels to the outside of the jar with clear packing tape, making sure to cover the label entirely. Please note that the ink from a “sharpie” marker or a pen will wash away when exposed to ethanol. If a sample requires multiple containers each container should have two labels and should be clearly marked as 1 of 5, 2 of 5, etc.

Internal labels can be printed on a laser printer using heavy card stock. Use a heavy weight cotton fiber paper (Rite in the Rain) and a No. 2 pencil or Pigma Micron pen if labeling by hand. Heavy card stock and pencil also work well for external labels.

Preservatives

The alcohol preservatives mentioned below are considered Hazardous Materials and MUST be packed and shipped according to Department Of Transportation rules.

And for Canada, all hazardous material must follow: IATA, International All Transportation Association and Transportation of Dangerous Goods.

The two most common preservatives/fixatives you will encounter are formalin (a solution of 5–10% formaldehyde and water) and ethyl alcohol (ethanol). Ethanol is preferred when shipping samples to the EcoAnalysts lab. Formalin is a toxic substance and requires special handling. Formalin’s acidic qualities may degrade many macroinvertebrates if not properly buffered.

Shipping Samples

When shipping samples to EcoAnalysts, please include a Packing Slip / Chain of Custody (C.O.C.) form. Please email Shanda McGraw an electronic version of your C.O.C. form listing all of your samples.

Download sample Chain of Custody form.

Use a reliable commercial shipping company (UPS, FedEx, DHL) when sending your samples. Please note the U.S. Postal Service does not handle hazardous materials of any kind. If practical, consider the many benefits of hand-delivering the samples.

International Clients: Please call us prior to shipping so we can make the proper arrangements with the appropriate U.S. agencies to import your samples.

Preserving Macroinvertebrate Samples

Ethanol is a potent enough fixative for most applications and is much safer to deal with. Careful attention must be paid to the final concentration of alcohol in the sample. Too high a concentration will cause the invertebrates to dehydrate and become brittle, and therefore make them very difficult for our macroinvertebrate taxonomists to identify. If the alcohol concentration is too low, the samples will not be adequately preserved and cause your invertebrates to decompose in their containers. For long term storage we recommend a solution of 70-80% ethanol. Since the water entrained in the sample usually dilutes the alcohol considerably, we recommend using a 95% ethanol solution in the field.

Adjust the amount of alcohol to the matrix of the sample. A good rule of thumb is a 1:1 ratio of preservative to sample material. If the sample is large and just barely fits in the jar, you are better off splitting it into separate containers to allow adequate preservation.

Invertebrates die and decompose remarkably fast, so don’t delay preserving them. If for some reason you are unable to use preservative in the field, put the samples on ice, out of direct sunlight, and preserve them as soon as possible. You may find that isopropyl alcohol (rubbing alcohol) is more readily obtainable. Isopropyl is a good alternative to pure ethanol, but make sure you get the technical grade (99%). Denatured alcohol is also available but is a less attractive alternative as it often contains toxic additives to that could cause the macroinvertebrates to become more difficult to identify.

Preserving Fish Samples

Fish samples should be placed in wide mouth plastic jars with screw on lids, please do not use glass jars.

The fish should originally be preserved in a 10% formalin solution for at least a week. For large specimens, it is a good idea to open the body cavity to allow the fixative to penetrate. After the specimens have been fixed by the formalin, they should be transferred to alcohol for long term storage. Do not use alcohol as a fixative, it does not preserve internal organs well and it tends to dehydrate the muscle tissue making the fish brittle.

Preserving Periphyton Samples

There are several preservatives available, Lugol’s solution and “M3” fixative are the best. You may also use buffered 4% formalin or 2% glutaraldehyde. For M3 a ratio of 20mL to 1L of sample is adequate for preservation.

• M3 Fixative

• 5g potassium iodide

• 10g iodine crystals (sublimed)

• 50mL formalin

• 1L distilled water

• Combine and dissolve.

Preserving Zooplankton Samples

Ethanol (at least 70% solution) or isopropanol (40%) are the preservatives of choice for samples that will be analyzed less than a year after they were collected. For long term storage (greater than one year), 2-4% formaldehyde is the only permanent preservative routinely used for zooplankton, though it is generally modified by the addition of several other chemicals – sodium borate, sugar, and/or BHT usually – for different purposes. Keep in mind that formaldehyde is recognized as a toxic, carcinogenic substance. Use alcohol whenever possible. For short-term preservation during shipping, a 2.5% solution of Lugol’s Iodine may be used. If Lugol’s is chosen, the samples will need to be transferred to ethanol immediately upon receipt. This must be coordinated with the lab prior to shipping.

Isopropyl Aclohol

If lab grade ethanol is unavailable, we suggest purchasing isopropyl alcohol over denatured alcohol as it is not as smelly and doesn't have nasty additives. Purchase the highest percentage of Isopropyl you can find. Stores should sell up to 70%, just make sure it isn't diluted too much with water and debris while collecting. Isopropyl should also be buffered with a few drops of glycerin and a pinch of calcium carbonate (crush antacid tablets), this keeps the organisms from becoming too brittle. If excess water is not added to jar and the jar is filled not more than half way with organic material and and the Isopropyl is buffered, this preservation will be good enough for long term storage.  

If you you end up using denatured ethanol, please follow the same guidelines and this solution should be buffered in the same fashion as isopropyl, which would allow for similar storage time.