>At 08:33 PM 5/25/98 -0700, you wrote:
>>I built a vacuum line to trap CO2 from atmospheric samples for isotopic
>>analysis a couple years ago, and initially tried a magnesium perchlorate
>>trap to remove water vapor from the samples.  The line produced poor
>>results for stable carbon isotopes.  While investigating potential
>>problems, we heard that magnesium perchlorate works fine near atmospheric
>>pressure, but does not perform well under vacuum.
>>
>>We elected to replace the magnesium perchlorate trap with a dry ice/alcohol
>>slush trap, and eventually got excellent results.  Unfortunately, we
>>changed several other aspects of our line at the same time, so I can't
>>conclusively say that this was the problem.
>>
>>While the isogeochem group is on this subject, I'd be very interested to
>>know if others have experienced problems with magnesium perchlorate at high
>>vacuum... or if these problems can be eliminated by using an anhydrous
>>variety.
>>
>>Thanks,
>>Troy
>>
>>PS.  Also a safety warning:  dry magnesium perchlorate can explode
>>violently when shocked severely.
>>
>>
>>Troy Baisden
>>Graduate Student
>>ESPM-Ecosystem Sciences
>>UC Berkeley     (510) 643-6910
>>
>>

Chemicals in many professions are always a concern and we deal with them on
a daily basis. WRT exploding magnesium perchlorate if shocked severely, I
have not heard of this and would be curious to the origin of this
information. Given my curious nature and a Bay Area neighbor, I had another
look at the full MSDS for magnesium perchlorate and could not find a
warning to this effect. However, they do state that magnesium perchlorate,
like so many other chemicals, may ignite or explode on contact with other
combustable materials. This list is long and is worth a look as are MSDS on
anything used in the lab.  My understanding from the MSDS is that magnesium
perchlorate by itself is reasonably stable.
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David A. Mucciarone
Stanford University
Department of Geological and Environmental Sciences, 320
Stanford, CA 94305-2115
650-723-0817 (office) 650-725-0979 (fax)
e-mail: [log in to unmask]
WWW: http://pangea.stanford.edu/~dam

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