[NHCOLL-L:4488] resitivity for water used in wet collections?

[Opitz, Cindy]

I’m new to processing wet collections-not a collector of new specimens, but faced with transferring existing collections into newer fluids, due to evaporation, etc.  I understand the transfer process, and I’ve been told I should use de-ionized water, but I’m unclear about what resistivity is desired for the de-ionized water we mix with ethanol for our storage solution. I have available to me a Type I system, including a sink spigot with water reading 13-15.4 MΩ, and a wall box that filters the same water to a reading of 18.3 MΩ.  Are both appropriate for using in storage (with ethanol) of natural history specimens, or do we really need that extra boost to an 18+ reading?  The sink spigot would fill our water container about 20 times faster than the wall box.
Our wet collections include leeches, crayfish, small rodents, reptiles, and amphibians, which have been collected over the past 150 years and until now have been stored in a variety of fluids (70% EtOH, 95%, and some formalin-based).  We’re standardizing to 75% EtOH.
I’m grateful for any advice you might offer!

Cindy Opitz
Collections Manager
Pentacrest Museums: Museum of Natural History
and Old Capitol Museum
11 Macbride Hall
The University of Iowa
Iowa City IA 52242
319-335-0481
www.uiowa.edu/~nathist<http://www.uiowa.edu/~nathist>
www.uiowa.edu/~oldcap<http://www.uiowa.edu/~oldcap>

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