[NHCOLL-L:1779] Determining between unknown concentrations preservative; isoprop anol & water and ethanol & water

[Robin McPhee]

Hi all,

We been given a possible chemical test method for determining between
unknown and widely varying concentrations of isopropanol and unknown and
widely varying concentrations of ethanol.  We don't wish to do the sniff
test, and density doesn't differentiate between the two alcohols, i.e. is a
reading of 55%, a weak soln of Ethanol or a good soln of isopropanol.

The method is (pers comm. Dave Appleton,  Auckland Uni. Chem. Dept.):
"First, mix 68 g on Zinc chloride with 52 g conc. HCl (ice cold) while
keeping it cold on ice. 
Leave solution for a couple of days. (Will need fume extraction).

To test the solution, take 1 mL of the alcohol and add 6 mL of the above
solution. 

Ethanol will remain clear and colourless, isopropanol should turn cloudy
over 5-10 min."

Has anyone tried or tested this on natural history spirit collections
solutions, or know of any other test?

Thanks and Cheers
Robin McPhee
Technical Officer, EEZ Fishes Project,
Fish Section
Museum of New Zealand, Te Papa
169 Tory Street
P.O. Box 467
Wellington, New Zealand.
Phone DDI 64 4 381 7308
Fax 64 4 381 7310
http://www.tepapa.govt.nz/our_resources/Fish_team/collection_fish.html


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