[ RadSafe ] LSC Method Assistance Needed - CO2

[CARTER Brian -NUCLEAR]

Hi Barbara,

This chain of emails was forwarded to me by a colleague and I would offer some thoughts on the subject.

I am assuming that you would like to stick with LSC, revise your process to use less nasty chemicals. You don't include too much detail on detection requirements, sample size and equipment available, so I will keep the comments generic.

If this is expired air, then unless you are using a fairly large volume (the amount of CO2 available) sample size will likely be an issue.

Since you are currently bubbling the sample through a mixture to capture CO2, you could simply use either sodium or potassium hydroxide as a replacement and count the resultant solution with one of the newer (safer) cocktails. Most of them can tolerate caustic solutions and chemiluminescence isn't much of an issue for C-14 counting if you raise the lower limit of the count window. A word of caution on cocktail selection, on the preparation tables that are available for these cocktails, they will state concentrations of caustic that can be safely used. This means safe for the cocktail, not your sample integrity. Many of them are strongly buffered to acidic Ph's, this of course will evolve the CO2 from the sample. Not sure of the rules in this forum, but I will suggest that Monophase may be a good cocktail for this purpose, we monitor carbonate waters and this is one of the better ones for that purpose.

These changes would get away from the organic compounds and move the process to a safer cocktail and simple caustic (which is still a hazard, just not as nasty), while maintaining an almost identical procedure. I can think of a few other suggestions that could "improve" the process, but they would require more knowledge of the application to see if they could actually be applied.

Brian Carter
HP - Environment
Ontario Power Generation

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of blreider at aol.com
Sent: Thursday, January 07, 2010 10:07 AM
To: radsafe at radlab.nl
Subject: Re: [ RadSafe ] LSC Method Assistance Needed - CO2



Thanks to those of you who have responded, I think your inputs have been helpful.  If anyone else who does a lot of LSC counting has additional input we would love to hear from you!

Barbara Reider, CHP






-----Original Message-----
From: blreider at aol.com
To: radsafe at radlab.nl
Sent: Wed, Jan 6, 2010 8:27 pm
Subject: [ RadSafe ] LSC Method Assistance Needed - CO2



One of my friends, a new HP, asked me if I could assist him in finding a better
ocktail for his SC work.  He writes:  "Our breath bioassay monitors 14CO2.  So
e have a solution that we make, and we bubble the air from the balloons in the
olution to trap the co2 and count it on our LSC.  This has been done for a long
hile, but the mixture is made up of some nasty stuff, so I just want to see if
e 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 and advice
 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 and advice
 am sure he will appreciate it.
hanks in advance.
arbara Reider, CHP

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