[Nhcoll-l] storage of 70% ethanol specimens at low temperatures for an extended period

[Alastair.Graham at csiro.au]

Hello all

Does anyone have any experience with storing preserved specimens at temperatures below 15°C (59°F) for an extended period?  Or, what is the lowest temperature that preserved specimens can be safely stored?

A portion of our fish collection needs to be re-located for 4-6 months (perhaps even longer) during building works.  Our specimens were originally fixed in 10% formalin and have been transferred to 70% ethanol for long-term storage.  The specimens are stored in 30 litre plastic drums (high density polyethylene), which have rubber gaskets.  I will be re-locating about 150 drums.  I had originally suggested hiring a hazardous materials shipping container with temperature control (15-22°C or 59-72°F).  However, such a container is proving difficult to source.  Now, a refrigerated shipping container has been suggested, although I do not know the temperature range it can be set at.

John Simmons in his Fluid Preservation - A Comprehensive Reference (2014) states on page 122 that the preferred storage environment for fluid collections is 18-21°C (65-70°F)".  Also on pages 103-104, John refers to a test where he placed jars of specimens in a refrigerator, demonstrating that the 70% ethanol turned cloudy below about 60°F (16°C).  "The cloudiness may have been caused by the formation of paraformaldehyde from the trace amounts of formaldehyde in the preservative, the congealing of lipids extracted by the alcohol, or other causes, but in any case, it was an unacceptable change in the preservative."

It has also been suggested that storing the specimens below 15°C and then moving them for examination to a lab at room temperature (22°C) could be harmful to the specimens.  Additionally, the humidity of the shipping container may promote mould growth on the drums.

Perhaps I have (or actually John in his book has) answered my question about what is the lowest temperature that specimens can be safely stored.  However, I would be interested to hear your views on storing specimens for an extended period below 15°C.

Cheers

Al

Alastair (Al) Graham
Fish Collection Manager
Australian National Fish Collection
National Research Collections Australia
CSIRO National Facilities and Collections

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