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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: mithunsugun on May 24, 2009, 12:39:55 AM

Title: citrate phophate buffer
Post by: mithunsugun on May 24, 2009, 12:39:55 AM

i m a research scholar. i came across an enzyme assay, and in which its needed to make a citrate phosphate buffer wit pH 6.5. could anybody give me some suggest the composition of the same. it wil b grateful...
thank u....

Title: Re: citrate phophate buffer
Post by: Rabn on May 24, 2009, 03:17:16 AM

I suggest Henderson-Hasselbalch.

Title: Re: citrate phophate buffer
Post by: Borek on May 24, 2009, 03:56:57 AM

Henderson-Hasselbalch equation (http://www.chembuddy.com/?left=pH-calculation&right=pH-buffers-henderson-hasselbalch) won't be easy to use - this is a mixture of triprotic acid (citric) and triprotic base (phosphate) and at pH 6.5 we have to take into account both third dissociation step of a citric acid and second step of the phosphate hydrolysis. Calculations will be complicated.

For all practical purposes it is much easier and much better to use my Buffer Maker (http://www.chembuddy.com/?left=Buffer-Maker&right=buffer-calculator) here than to calculate such  buffer by hand.