Jump to content

  • Log in with Facebook Log in with Twitter Log in with Windows Live Log In with Google      Sign In   
  • Create Account

Submit your paper to J Biol Methods today!
Photo
- - - - -

Change of pH of Phosphate buffer with Imidazole


  • Please log in to reply
1 reply to this topic

#1 vrram

vrram

    member

  • Members
  • Pip
  • 1 posts
0
Neutral

Posted 03 August 2010 - 05:41 AM

Hi all,

I am preparing a set of phosphate buffers for my protein purification. I have the stock phosphate buffer 500 mM pH 7.8. I dilute to make 20 mM buffer. However, If I add NaCl (500 mM) and Imidazole (20, 50 and 500 mM) the pH changes considerably. In that case, how to make the final pH to 7.8? Can I add HCl or one of the phosphate solutions to adjust the pH? Will it not affect the ionic strength of the final buffer? I want all the buffers at same pH and ionic strength as I am going to use them for gradient wash/elution.

Many thanks in advance.

-Raj

#2 mdfenko

mdfenko

    an elder

  • Active Members
  • PipPipPipPipPipPipPipPipPipPip
  • 2,781 posts
131
Excellent

Posted 03 August 2010 - 06:36 AM

the imidazole is causing the change in pH. imidazole is a buffer (pK 7.0). you can preadjust a stock of imidazole or adjust in the solution (don't use phosphate, you want that to remain constant). any change in ionic strength should be inconsequential.
talent does what it can
genius does what it must
i do what i get paid to do




Home - About - Terms of Service - Privacy - Contact Us

©1999-2013 Protocol Online, All rights reserved.