RE: "Radaway Filter"

["Quang Le"<qmle@icnpharm.com>]

We tried this filtering system a few months ago. Even though the principle
sounded great, practically, we did encounter some problems.

We tried this filter on our HPLC waste. Because this waste is typically
rather thick in consistency, it took a very long time to filter just 500 mL
(~2 days) using gravity. We next tried applying vacuum as suggested by the
manufacturer. This sped up the process a bit but we encountered a different
problem. The filters that we tried broke under pressure. We did not measure
the exact vacuum applied. We just kept increasing the vacuum until the
liquid flows at an acceptable rate (<2 hrs per 500 mL of liquid filtered).

After several unsuccessful tries, we abandoned the idea for the following
reasons:

1)   This system could only filter ~50% (that's what our numbers showed for
the first few "gravity" runs) of the radioactivity, per run.
2)   It took too long without vacuum. With vacuum, this operation must be
supervised. I would not just start it and walk away or risking having a big
mess (not only the filters but the collection compartment also broke
spilling radioactive liquid in our hood)

The manufacturer told us they did encounter some filter breakage also but
they corrected the problem. So maybe the newer filters won't break anymore.
Depending on the waste you are trying to filter, you may be able to find an
acceptable (and safe) flow rate.

Note that our experiments were, by no means, scientific (we did not care if
they were). Practically, this system did not work for us.

Hope this help.

Quang Le
<qmle@icnpharm.com>
ICN Biomedicals