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Regarding ether hazards when cleaning the top objective lens, I do only use
a working 10ml bottle of ether [stored in our flammables cabinet], not a 2.5
l winchester - and I open the lid, dip in the cotton bud and re-screw the
lid immediately [I don't pour it onto lens tissues]. The advice is to use
diethyl ether in 'well ventilated areas' [rather than 'fume cupboard' only].
Ether explosion limits are 1.7% to 48% compared to alcohols 3.3% to 24.5%
[although ether does evaporates at a far higher rate]. In our lab should the
whole 10ml evaporate the air concentration would be about 0.00035%, around
5,000 times lower than the explosion limit, and the room is well ventilated.
That said diethyl ether boils at 34.6oC and being denser than air its
creeping, volatile and highly flammable nature is pretty impressive - see
The Ether Trough video at
http://www.angelo.edu/faculty/kboudrea/demos/ether_trough/ether_trough.htm
Hence Stan's important comments on avoiding naked flames in the lab when
ether is about.
I suppose absolute alcohol is also highly flammable, and here we have litres
of that about in the lab. Diethyl ether has additives to reduce explosive
byproducts [unstable peroxides left after evaporation].
Methanol is toxic by inhalation, rather than harmful as for ether and
alcohol, and personally I probably wouldn't use it over ether or alcohol.
But again it's small volumes in the fume cupboard, and we use
methanol/acetic acid a lot as a fixative.
For an interesting discussion of ether used as a recreational drug [it's
effects are similar to alcohol, although you sober up far faster] see:
http://www.druglibrary.org/schaffer/library/studies/cu/cu43.html
Regards
Keith
Advice for labs, schools and colleges:
http://cartwright.chem.ox.ac.uk/hsci/chemicals/ethyl_alcohol.html
http://cartwright.chem.ox.ac.uk/hsci/chemicals/diethyl_ether.html
http://cartwright.chem.ox.ac.uk/hsci/chemicals/methanol.html
http://cartwright.chem.ox.ac.uk/hsci/chemicals/hsci_chemicals_list.html
---------------------------------------------------------------------------
Dr Keith J. Morris,
Molecular Cytogenetics and Microscopy Core,
Laboratory 00/069 and 00/070,
The Wellcome Trust Centre for Human Genetics,
Roosevelt Drive,
Oxford OX3 7BN,
United Kingdom.
Telephone: +44 (0)1865 287568
Email: [log in to unmask]
Web-pages: http://www.well.ox.ac.uk/molecular-cytogenetics-and-microscopy
-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On
Behalf Of Stanislav Vitha
Sent: 17 March 2011 14:50
To: [log in to unmask]
Subject: Re: Cotton wool for lens cleaning
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*****
I agree,
ether is not good for you. I should have mentioned the obvious - that there
should not be any open flame in the room, and that I do the objective
cleaning
in a chemical hood.
Stan Vitha
On Wed, 16 Mar 2011 21:22:59 -0400, Nina Allen <[log in to unmask]>
wrote:
>Long ago we taught using ether in the fashion described here. Ether is
very
flammable. It is also not good for you.
>So even if it works well it is not a recommended method.
>
>Nina Allen
>Professor Emerita
>Department of Plant Biology
>North Carolina State University
>
>Sent from my iPhone
>
>On Mar 16, 2011, at 6:45 PM, Stanislav Vitha <[log in to unmask]> wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Hi Aleksandrs,
>>
>> I like to use the method where you clean the lenses without touching
them.
>> I learned this from Karl Aufderheide when he was showing this trick to my
LM
>> course students.
>>
>> 1. Don't touch anything (even lens paper) to a lens surface except as a
last
>> resort. Avoid especially commercial facial or bathroom tissue because it
could
>> contain diatom frustules (glass!) as a filler. One pass of a kleenex over
a
lens
>> could possibly ruin it!
>> 2. Hold a piece of lens paper or other tissue over a lens. Place a few
drops
of
>> ethyl ether on the paper and draw the paper across the lens surface so
that
>> the ether flows rapidly in a circular pattern over the recessed lens
surface.
In
>> this way, the ether contacts the lens but the paper does not, because the
>> lens is recessed.
>> 3. Inspect the lens using an inverted ocular as a magnifier. Repeat the
ether
>> wash if necessary.
>> 4. If ether does not remove the dirt, try first distilled water, then
chloroform,
>> then xylene or benzene, in that order. If all else fails, try a 1:1:1
mixture of
>> water, alcohol and chloroform shaken just before use. Follow with an
ether
>> wash.
>> 5. For stubborn dirt (e.g., on old student microscopes) use the above
solvents
>> on a clean Q-tip.
>>
>>
>> Because of safety concerns with ether (formation of explosive peroxides),
I
>> just get a fresh bottle every 6 months, and dispose of the old one
through
our
>> Hazardous Waste program.
>>
>> Stan Vitha
>> Microscopy and Imaging Center
>> Texas A&M University
>>
>> On Tue, 15 Mar 2011 15:03:31 -0400, Aleksandrs Spurmanis, Mr.
>> <[log in to unmask]> wrote:
>>
>>> Dear list,
>>>
>>> The current practice at our facility is to inspect and clean the
objectives
of
>> our scopes periodically (approx. once every 2-3 months for each scope)
using
>> lens paper wrapped around small clean-room swabs. I had noticed,
however,
>> that the field service technicians who run the PMs on our instruments
tend
to
>> use 100% cotton wool (which I understand to be essentially the same
material
>> as your basic 100% cotton ball in the pharmacy) and are able to service
our
>> lenses in a much more efficient manner (read: waayyy quicker) than myself
>> using my current methods. In the interests of improving my maintenance
>> efficiency, I've been considering trying this out myself but wanted to
check
in
>> with the list to see if anyone can share their experiences, insights or
advice
>> before proceeding. My main concern is that the cotton might contribute
to
>> premature wear on the lens coating. As cleaning solvents, I use either
Glass
>> Plus, anhydrous ethanol and/or water.
>>>
>>> Thanks in advance.
>>>
>>> Sincerely,
>>>
>>> Aleksandrs J. Spurmanis
>>> Microscopy Specialist
>>> Imaging Facility
>>> McGill University Life Sciences Complex
>>> Francesco Bellini Building
>>> 3649 Sir William Osler
>>> Suite 137
>>> Montreal, QC
>>> H3G 0B1
>>> tel.: (514)-398-5248
>>> fax: (514)-398-7452
>>> [log in to unmask]
>>> http://www.mcgill.ca/lifesciencescomplex/core/imaging/
|
