fluorescein diacetate (fda)

Posted by Aryeh Weiss on
URL: http://confocal-microscopy-list.275.s1.nabble.com/fluorescein-diacetate-fda-tp7592130.html

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I am using fluorescein diacetate in my teaching lab. The student get to
see the cells light up, measure the increase over time (takes a minute
or two), see it photobleach afterwards, and  process it by subtracting
the in-cell signal from background fluorescence. Very nice.

My question concerns the storage of the fda. We made a 0.5mM stock
solution in acetone, which worked great with a further 1/200 dilution
into the plate. We could probably have also diluted 1/1000.
We stored the leftover stock solution at -20C. A week later that stock
solution did not work at all. When we added 10ul to cell culture plate ,
we saw an increase in background, but absolutely nothing in the cells.

We then made a fresh stock solution of fda, and it worked perfectly.
Exactly as expected.

So my question is - what happened?

Is there  a trick to keeping the stock solution active, or do we need to
make it fresh every week?

Thanks for any advise you can provide.

--aryeh

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Aryeh Weiss
Faculty of Engineering
Bar Ilan University
Ramat Gan 52900 Israel

Ph:  972-3-5317638
FAX: [phone]