I think the problem is that Britannica, or even Wikipedia, is and has never been the final arbiter of truth, I would put my faith in a specialist publication such as:
http://books.google.co.uk/books?id=bwbCVCFPNI4C&pg=PA175&lpg=PA175&dq=%22karl+hasselbalch%22&source=web&ots=yHzTUiNE1g&sig=7JmNU-OfHIkmXxR5ivGTrpS7_Us&hl=en&sa=X&oi=book_result&resnum=5&ct=result
-- Ian
> -----Original Message-----
> From: [log in to unmask]
> [mailto:[log in to unmask]] On Behalf Of William Scott
> Sent: 07 August 2008 23:27
> To: Juergen Bosch
> Cc: [log in to unmask]
> Subject: Re: [ccp4bb] Ammonium citrate tribasic buffer
>
> Wikipedia claims Hasselbach is a misspelling:
>
> http://en.wikipedia.org/wiki/Henderson-Hasselbalch_equation
>
> Since Wikipedia has now replaced the social consensus as the final
> arbiter of truth ...
>
>
> On Aug 7, 2008, at 3:22 PM, Juergen Bosch wrote:
>
> > Just on a side note, can someone clarify why Hasselbach is not
> > Hasselbalch or vice versa ? Or is that the same guy just somewhere
> > sometime misspelled and for ever in the records ?
> >
> > See here:
> >
> http://www.britannica.com/EBchecked/topic/261188/Henderson-Has
selbach-equation
> >
> > Jürgen
> >
> >
> > On 7 Aug 2008, at 15:12, [log in to unmask] wrote:
> >
> >> Good points!
> >>
> >> Not only citrate is inappropriate for buffers in the pH 6.5-7.5
> >> range,
> >> but also (as pointed out by your colleagues at UCSC, but
> probabbly
> >> elsewhere,
> >> polyprotic acids are hard to handle, as their pKa change in a
> >> significant
> >> fashion depending on their concentration.
> >>
> >> In this case, the Henderson-Hasselbalch equation must be
> written in
> >> terms
> >> of activities rather than concentrations, otherwise it is totally
> >> useless.
> >>
> >> Nadir Mrabet
> >>
> >>
> >>
> >> Selon "William G. Scott" <[log in to unmask]>:
> >>
> >>> There are 3 pKa's for citric acid:
> >>>
> >>> 3.15, 4.77, and 5.19
> >>>
> >>> so it is going to be a lousy buffer at pH 6.7 to 7.25.
> Also, you
> >>> need
> >>> to know what concentration your buffer is, and whether that
> >>> concentration is with respect to the citrate ion or what. It
> >>> won't be
> >>> tribasic with respect to ammonium ion near neutral pH.
> >>>
> >>> So if for example you need 1M of this buffer, the simplest thing
> >>> to do
> >>> is make up a 1M stock solution of tribasic ammonium
> citrate and a 1M
> >>> stock solution of of citric acid and then mix the two
> together. You
> >>> can calculate the ratio using the Henderson-Hasselbalch
> equation or
> >>> just titrate one into the other while stirring in the
> presence of
> >>> a pH
> >>> electrode.
> >>>
> >>> (You'll have to use the pH electrode approach if you took
> >>> introductory
> >>> chemistry from anyone other than me at UCSC since my colleagues
> >>> think
> >>> that polyprotic acids are too stressful for our undergrads.)
> >>>
> >>>
> >>> William G. Scott
> >>>
> >>> Contact info:
> >>> http://chemistry.ucsc.edu/~wgscott/
> >>>
> >>>
> >>> On Aug 7, 2008, at 12:42 PM, E rajakumar wrote:
> >>>
> >>>> Dear All
> >>>> Sorry for non crystallographic query.
> >>>> Can any body mail me how to prepare Ammonium citrate
> >>>> tribasic (citric acid triammonium salt) buffer pH 6.7
> >>>> to 7.25 and also what is the pKa value.
> >>>> Thanking you in advance
> >>>> Rajakumara
> >>>>
> >>>>
> >>>>
> >>>> E. Rajakumara
> >>>> Postdoctoral Fellow
> >>>> Strcutural Biology Program
> >>>> Memorial Sloan-Kettering Cancer Center
> >>>> New York-10021
> >>>> NY
> >>>> 001 212 639 7986 (Lab)
> >>>> 001 917 674 6266 (Mobile)
> >>>>
> >>>>
> >>>>
> >>>> Get your new Email address!
> >>>> Grab the Email name you've always wanted before
> someone else
> >>>> does!
> >>>> http://mail.promotions.yahoo.com/newdomains/aa/
> >>>
> >>
> >>
> >> Pr. Nadir T. Mrabet
> >> Cellular & Molecular Biochemistry
> >> INSERM U-724
> >> UHP - Nancy 1, School of Medicine
> >> 54505 Vandoeuvre-les-Nancy Cedex
> >> France
> >> Tel : +33 (0)3.83.68.32.73
> >> Fax : +33 (0)3.83.68.32.79
> >> E-mail : [log in to unmask]
> >
> > -
> > Jürgen Bosch
> > University of Washington
> > Dept. of Biochemistry, K-426
> > 1705 NE Pacific Street
> > Seattle, WA 98195
> > Box 357742
> > Phone: +1-206-616-4510
> > FAX: +1-206-685-7002
> > Web: http://faculty.washington.edu/jbosch
>
>
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