air monitoring w/bubblers -Reply

[FRAMEP@ORAU.GOV]

Glenn Sturchio wrote in part;
>Our question:  Does anyone have experience (or hints) on using
>bubblers for C-14 compounds other than CO2?  We're currently using
>ethanolamine.  How about S-35?
>We intend to run some bench top experiments, but any additional
>guidance would be appreciated.

Glenn, some references and comments.  The references do not describe
methods that are specifically designed for radionuclides however.
Please let us know what you end up doing and the results of your
experiments.  

ASTM D 2914 "Sulfur dioxide content of the atmoshpere- West Gaeke
Method" This method uses tetrachloromercurate as the bubbler
solution.

ASTM D 3449 "Sulfur dioxide in workplace atmospheres - barium
perchlorate method" This method use hydrogen peroxide as the bubbler
solution.

EPA 40 CFR 60 App A "Standards of performance for new stationary
sources" Methods 6, 8, 16 and a few others describe the use of
bubblers containing hydrogen sulfide for the collection of sulfur
dioxide. Method 16 also describes the use of a catalytic heater to
collect other forms of sulfur.

EPA 40 CFR 61 App B Method 114 "Test methods for measuring
radionuclide emissions from stationary sources" simply says
"radionuclides in the form of carbon dioxide may be collected in
caustic solutions"

It was in the early 80s, i.e. a long time ago, but I sampled a couple
of stacks for C-14 using bubblers (actually Greenberg Smith
impingers). We used NaOH as the collecting solution. It was a little
bit of a pain for the lab because the C-14 had to be precipitated out
of the NaOH with barium and redissolved before it could be counted.
The ethanolamine you use might be better because, unless I'm
mistaken, it can be transferred directly into a LSC cocktail.

For S-35 we used hydrogen peroxide, 3%, if I remember right, 50 mls
per bubbler, a flowrate of around 0.1 to 0.5 lpm and a 24 hour
sampling time (same flows, volume, times as for the C-14). Not being
a lab person, I didn't pay attention to the analysis, but I believe a
1 ml aliquot of the hydrogen peroxide went straight into the LSC
cocktail. 

We always ran with two bubblers in series followed by a dry trap to
keep entrained moisture out of the flowmeter and pump. For C-14 , and
S-35 if I remember right,  we used a catalytic furnace to convert the
organic stuff into oxides just as you are doing with H-3. same
principle, same practice. I don't believe we had this problem but if
the bubblers upstream of the heater let some CO2 through, it could
end up in the downstream bubblers and appear to be organic. The
biggest problem we had was leaks in the lines and bubblers. That and
the time our shop people decided to do us a favor and "clean out" our
catalytic heaters by dumping about a thousand dollars worth of
palladium into the trash.

It is possible that your solutions for CO2 collection might pick up
SO2 and the solution for SO2 might pick up CO2. This needs to be
considered wrt the analysis because the beta energies of S-35 and
C-14 are similar. Given time, you could measure the decay of the
activity and distinguish the C-14 and S-35 based on half life.

I hope this helps a little. Have fun with the experiments, we don't 
get to do enough of that in this business.

Paul Frame
Professional Training Programs
Oak Ridge Institute for Science and Education.
framep@orau.gov