PBS had turned cloudy upon autoclaving. I used milliQ water for preparation of PBS with proper ingredients but it became cloudy upon autoclaving.
Dear Ganesh,
Upon autoclaving or freezing one of the components such as sodium dihydrogen phosphate or disodium hydrogen phosphate comes out of the solution and makes it cloudy. Instead of autoclaving the PBS, you can sterilize the solution via passing it through vacuum 0.2 micron filter.
For more on this topic, please see the following link:
http://www.protocol-online.org/biology-forums-2/posts/11659.html
Hoping this will be helpful,
Rafik
Never happened to me and I usually prepare a 10X PBS. Always in borosilicate glass.
What's your recipe? Do you include Ca? if so, you have calcium phosphate precipitation and will happen every time you autoclave. If not...
Do you add any alkali to adjust pH? Is it stored in glass? If so, you have Ca contamination in the buffer, specially if the alkali concentration is high and has been stored for long. The effect would be the same I described above.
Xabier, I do not use CaPO4 neither do I adjust pH. Thank you for the reply.
What I meant is that if you have a Ca salt, it may precipitate as calcium phosphate during autoclaving.
USE MILLIQ WATER FILLED INTHE AUTOCLAVE FOR GENERATING STEAM
OR PROBABLY U CAN FILTER STERILIZE WITH 0.2 MICRON MEMBRANE FILTER
It happened to me, too. I was using DI water. The water here at OSU is very hard so some of the minerals were causing precipitates. Once I switched, to millipore water it didn't happen anymore.
Oh It happens to me today, what do you have to do with it, Throw it away?
Some people might not want to use it. Depends on the application. I used it for washes and things like that, when it happened to me.
Patricia Boley Thank you, after PBS was autoclaved, it looked cloudy, but when it adjusted to room temparature, It turns to be clear, so I used it for washing and I think It's okay
Make it using millipore water from now on. I don't think it is bad because it is cloudy. It just may not be full strength because some of the metal ions are not fully soluble.
it happens to me also, same case, so, i will filter my Phosphate buffer with sterile 0.2 µm filter, and use it for protein suspension.
I would not recommend to filter as this will remove some phosphate and effect the buffer capacity and pH of the solution. Check the MilliQ resistance to make sure it is working properly. Rinsing the glassware with a very dilute acid (0.001 HCl) in milliQ water can also help remove residual calcium salts left over from washing glassware.
It also depends on how pure your phosphate salts are. When I dissolved it from a bottle made in the 1990s for general use, it always turned greyish after autoclave, even when I used Milli-Q water. I looked at the component sheet, and it said some percentage about Ca. I encountered no more precipitates after switching to the one manufactured in the 2010s and a higher grade.
Most precipitate would be hydroxyapatite Ca10(PO4)6(OH)2 .
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