Shipping Frozen Samples w/o Using Dry Ice

Question

I am having some cetacean skin samples sent to me from overseas for C and N analysis (for a feeding ecology study). The samples will be in transit for approximately 72 hours. I cannot use dry ice to keep the samples frozen and the folks sending them to me are unable to dry the tissue. Any thoughts on how, if at all, this might affect the C and N signatures of the tissues? And if the consensus is that this will have a dramatic affect on the numbers, any suggestions on how to preserve the tissues during transit to avoid this?

Nicole Browning, University of Central Florida

Answer

A neat way to keep things cold (ca. 0°C) for 3-4 days is to place the samples in 1.5 ml Eppendorf tubes. Then, take a wide-mouthed thermos flask (metal or plastic), place the samples within it and then almost fill with water.

Without putting the top on, place the whole thing upright into a -20°C freezer for a day or so. When it is completely frozen, top up with water, and place the top on the flask.

When you are ready to ship the flask, they can wrap it in a towel or something similar to insulate it. I have brought samples from Trindad to Germany in this way, and they were still frozen 4 days after I set out (I know, because my bags got lost by the airline!).

Alternatively, air-dry the samples (over a radiator?). I sometimes make a small washing line where I dry thin sections of muscle tissue in 2-3 days. They could just stick them in alcohol or even salt?

Preservation will have a small effect, but most studies indicate it is minimal....

Dr Chris Harrod, Queen's University Belfast, UK