[Nhcoll-l] CPD advice

[Doug Yanega]

On 5/8/14 3:00 PM, Copley, Claudia RBCM:EX wrote:
>
> Hi everyone
>
> Our "classic" critical point dryer finally gave up, so I am trying to 
> figure out what would be suitable for the needs of the natural history 
> section here at the museum but especially the entomology department 
> --micro-Hymenoptera and Diptera predominantly. I am also hoping to be 
> able to afford something fully automated, but with the usual museum 
> limits on budgets. Does anyone have anything good or bad to say about 
> a fully automated CPD you're using?  Recommendations? ballpark 
> pricing? perfect for an entomology collection...!
>
>
Since we dehydrate thousands of insects every year, I can offer two 
things: (1) We have an automated unit, a Tousimis Autosamdri, that has 
worked *reasonably* well for 12 years now. I don't think they still 
offer the same unit, and while it's only broken down twice, the repairs 
took a long time. It does require a constant supply of large CO2 
cylinders, and we had to drill a hole in our outer wall for the vent. 
(2) We ALSO use chemical CPD processing, with HMDS 
(hexamethyldisilazane), and as alternatives go, the pros and cons of 
HMDS are noteworthy: the chemical is fairly expensive, and it takes a 
few hours and a fume hood to do it properly, BUT (a) one can do a larger 
total number of specimens per unit time if the technician has a lot of 
samples lined up and ready to go, and is willing to spend three hours 
not doing anything else (b) one can process larger volumes of specimens, 
and larger actual specimens, than can fit inside the tiny CPD chamber 
(for example, you can dehydrate mantises, walking sticks, katydids, etc.)

For us, then, a lot depends on who we have doing the processing, and the 
number of samples being processed; for full-time staff, or for single 
samples, we'll use the CPD unit so we can put it in the machine and 
forget it. For hourly workers or large numbers of samples, we use the 
HMDS. BTW, an anecdotal observation we've heard and have not yet heard 
refuted, is that HMDS-treated specimens are actively avoided by 
dermestid larvae, and therefore potentially immune to being consumed.

Peace,

-- 
Doug Yanega      Dept. of Entomology       Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314     skype: dyanega
phone: (951) 827-4315 (disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82

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