buffer preparation - (Nov/12/2007 )

hi guys,



it's the first time for me to prepare a buffer...so i need your help to understand the whole way step by step..i read that we have to use Henderson-Hasselbalch Equation...what else!? and i noticed the use of NaOH?

for example, how to prepare 200ml phosphate buffer of 200mM with a pH of 8!

If I'm not wrong, it's an equation to calculate the amount of acid or alkali to add to get a precise pH.
I never use it.

here are tables that help you to prepare some buffers.

http://molbiol.ru/eng/protocol/01_02b.html#a48a

for phosphate buffer (I prefer K instead of Na, because it doesn't precipitate in the fridge), you add 94 mL K2HPO4 1M to 6 mL KH2PO4 1M. You get a 1M phosphate buffer, pH 8.0. Then you dilute it 5 times to get a 200 mM phosphate buffer pH 8.0

yah..
l agree with missele.
now a days all buffer comming as Tabs.

be good and cool in calculations all preparetions become easy to U

Regards
Siva

what missele has told you is correct, in theory. in practice, you will probably have to perform some final adjustment of pH with the acidic or basic stocks. this will not change the concentration of the buffering ion, only the volume.

thanx guys for help
i read also about this topic and understand moe about it...but what affects a buffer capacity?! its PKa!??

thanx guys for help
i read also about this topic and understand moe about it...but what affects a buffer capacity?! its PKa!??