Make PBS with Calcium and magnesium? - (Feb/04/2005 )

First i make PBS 10X as stock solution. I dilute it to have PBS1X and after I add CaCl2 and MgCl2. But when I add CaCl2, my solution make a precipitate which doesn't disappear after sterilization. How to do? Please help me.

-Valmice-

I was wondering why you are adding CaCl2 and MgCl2 to PBS?

Also what amount of these two compounds are you adding to the PBS, maybe with an already high salt concentration (saturated) no more salt will go into solution and hence your precipitate even after autoclaving.

Cheers

Nick

-methylnick-

QUOTE (methylnick @ Feb 5 2005, 03:43 AM)

I' m wondering the same question... why do you add CaCl2 and MgCl2 to PBS?

-aleksy_100-

QUOTE (methylnick @ Feb 5 2005, 03:43 AM)

I want to add CaCl2 and MgCl2 to keep the integrity of early mice embryos.
the amount of CaCl2 is 0,133g and MgCl2, 0,1g. But it is only when I add CaCl2 that my solution precipite. MgCl2 doesn't do that!!!

-Valmice-

Oh okay,

which CaCl2 are you using?

Anhydrous CaCl2 doesn't go into solution, you would need the powder that has water within it, ie: CaCl2.2H2O (calcium clhoride dihydrate). I tried to dissolve anhydrous CaCl2 with no luck at all.

That should solve the problem! Just another question, what volume of PBS are you making for that amount of powder added???

Cheers
Nick

-methylnick-

The thing is that PBS with Ca and Mg will precipitate IN THE FRIDGE. We keep in on the bench.
We prepare two 20X solution which we dilute to 1X, if you try to make directly 1 solution of 20X, it will precipitate..
So for 1 liter of each 20X...

solution A : 348mM Na2HPO4... 46.86g
70mM NaH2PO4.... 9.66g

solution B : 18mM CaCl2... 2.6g
70mM KCl... 5.2g
18mM MgCl2... 3.6g
2740mM NaCl... 160g

take 5ml of each in 90ml of water, and you have 1X PBS... do not refrigerate.

Simon

-Simonsays-

QUOTE (Simonsays @ Feb 9 2005, 09:28 AM)

Thank you very much for this information, my solution doesn't precipitate

What a luck!

-Valmice-