Ammonium hydroxide vs Ammonium carbonate
Chris J. Durden
drdn at mail.utexas.edu
Wed Apr 19 01:51:25 EDT 2000
At 08:19 16/04/00 -0600, you wrote:
>Jean-Francois Landry & Bernard Landry, J. Lep. Soc 48(1): 208, advocate
>laboratory grade (30% ammonia, 70% water) ammonium hydroxide solution for
>despatching microleps. The latest Bioquip Catalog does not have ammonium
>hydroxide but has ammonium carbonate instead. The latter is in a powder
>form, some of which is placed in the bottom of a collecting vial and
>activated by the addition of some water. In other words, it would be used
>as in the old fashioned potassium cyanide killing jars I used to use.
>My question is which of the above is best, ammonium hydroxide or ammonium
>carbonate, and does anyone have any tips about their use? Could either be
>used with a UV light trap, or would ethyl acetate be best?
The biggest problem with use of ammonia as a killing agent is the effect
it has on colors if there is water present. Colors, particularly oranges
and reds are soluble in condensation with dissolved ammonia, leaving stains
and fading on the specimen.
If your killing tube is dry and you have a set of replaceable caps/corks
with recess for absorbent cotton to take a drop of ammonia - this is an
excellent method. Under tropical conditions you may want to include silica
gel in the design.
For collecting at a light sheet, using net, large moths, especially
sphingids may be injected in the back of the thorax (under a hind coxa),
from the underside, with a mix of half "stronger ammonia" and half
isopropyl alcohol. Inject only a minute amount. Ammonia is the quickest
arthropod killing agent I know of. Don't jab your finger.
Household ammonia from the supermarket is no good for this. You must ask
for "stronger ammonia" or "aqua ammonia" at an old fashioned drug store if
you can find one. You will notice the different strength immediately as you
uncap at arms' length.
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