3 replies to this topic

[Flopilus]

I'm preparing an extraction buffer for RNA which has 4 M guanidine thiocyanate, 100 mM Tris-HCl, pH 8.0, 25 mM sodium citrate pH 8.0 and 0.5% N-lauryl sarcosine.
I'd like to know how to bring the sodium citrate solution to that pH, only by dissolving the drug in water?
and, can i autoclave it before adding it to the buffer solution?

Besides, all I have in my lab is N-lauryl sarcosine sodium salt, which I believe is used in RNA/DNA extraction protocols, but I'm not sure to use it likewise...

And finally, can I autoclave the finished buffer?

Thanks in advance!

[mdfenko]

never autoclave a solution that contains a detergent.

add all the components (except detergent), adjust the pH, (add the detergent) then bring to final volume .

filter sterilize.

Edited by mdfenko, 12 January 2012 - 08:33 AM.

[Flopilus]

I've autoclave another buffer with CTAB before and it worked perfectly, don't know why you say I can't...

What I want to know is how to bring to pH 8 the sodium citrate solution (it has a pH of around 9.5 at 100mM), and if I can autoclave it then.

Thanks

[mdfenko]

many detergents will solidify when heated. it's just better to avoid if not sure.

you can adjust the citrate the same way you adjust any buffer salt, you can use an acid compatible with your solution or equimolar citric acid to reduce the pH (if separate from the final solution).

citrate can be autoclaved.