[ RadSafe ] LSC Method Assistance Needed - CO2

[blreider at aol.com]

Thanks for your input and query Darren and Dave.  

Dave:  I do think you have a valid question - when doing any procedure a calibration should quantify all aspects of the method used, not just the count to disintegrations ratio.  I have not used this method for bioassay myself (this really was a question from someone else) so perhaps others have the answer about quantification of losses.

I have witnessed transport of tritium through just about any o-ring in creation.  It does take some time though, and I would think tritium exchange is a much faster exchange than C with the C of rubber.  Don't know about other mechanisms such as rubber pore sixe issues but if not held for long perhaps this method of collection does not create big errors or losses.

That said, iodine adsorbing on the walls of collection tubes from stack monitors seems to be always a problem.  Results resulting from isotopic isokinetic sampling is in many cases lower than the actual concentrations.  

2 cents!

Barbara Reider, CHP




-----Original Message-----
From: neildm at id.doe.gov
To: Daren.Perrero at illinois.gov; blreider at aol.com; radsafe at radlab.nl
Sent: Thu, Jan 7, 2010 7:25 pm
Subject: RE: [ RadSafe ] LSC Method Assistance Needed - CO2


I just noticed something about the process outlined in the request.
erhaps I am making an assumption, but use of a rubber balloon for
ollection of a sample analyzed for CO2 has the confounding factor that
O2 will dissolve through rubber and escape, or so I understood. 
Wrong?  Not Applicable? 
Just a comment.
Dave Neil
-----Original Message-----
rom: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
ehalf Of Perrero, Daren
ent: Thursday, January 07, 2010 3:27 PM
o: blreider at aol.com; radsafe at radlab.nl
ubject: RE: [ RadSafe ] LSC Method Assistance Needed - CO2
In a previous life in a land far far away, we conducted similar tests in
he same manner on respired air for the presence of H-3.  Our method
imply involved passing the respired air through several loops of super
ooled tubing immersed in liquid nitrogen.  Thus we were able to avoid
color quenching' and nasty issues associated with other bodily fluids
ince the collection/extraction solutions we gathered were essentially
ll water.  After that we were able to pick and choose our scintillation
ocktails based on their ability to deal with aqueous solutions for
aximum efficiency.
The opinions expresses are mine, all mine.....
'm with the government and I'm here to help you (ack!)
aren.perrero(a)Illinois.gov
-----Original Message-----
rom: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
ehalf Of blreider at aol.com
ent: Wednesday, January 06, 2010 7:27 PM
o: radsafe at radlab.nl
ubject: [ RadSafe ] LSC Method Assistance Needed - CO2

One of my friends, a new HP, asked me if I could assist him in finding a
etter cocktail for his SC work.  He writes:  "Our breath bioassay
onitors 14CO2.  So we have a solution that we make, and we bubble the
ir from the balloons in the solution to trap the co2 and count it on
ur LSC.  This has been done for a long while, but the mixture is made
p of some nasty stuff, so I just want to see if we can do better." 
The method they use a toluene based cocktail:  "solution that contains
oluene,sodium hyrdroxide, trimethylbenzene, and methyl glycol."
t has been a long time since I did LSC so if you have any experience
nd advice I am sure he will appreciate it.
hanks in advance.
arbara Reider, CHP 
It has been a long time since I did LSC so if you have any experience
nd advice I am sure he will appreciate it.
hanks in advance.
arbara Reider, CHP
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