Sorry about the formatting of the preceding message. Here is the
Three years ago, I wrote a program named CABUFFER that allows you to
calculate the free concentrations of all ionic species in a mixture of
up to four divalent ions (e.g. Mg, Ca, Sr, Ba) and up to four
different divalent ion buffers (e.g. EGTA, EDTA, NTA, HEDTA, citrate
etc.). Free parameters are temperature, pH and ionic strength. The
program was written in structured Basic and compiled with Borland's
Turbo Basic v. 1.0 or with Microsoft's Quickbasic v 4.0 under MS-DOS.
It runs very fast on PC's outfitted with a math coprocessor. A
slightly less capable program, CABUF, that runs reasonably fast even
on machines without math coprocessor is also available. At that time,
and perhaps still now, CABUFFER probably was one of the best and most
flexible programs of that sort available in the public domain.
This program has been passed around and is presently being used by a
number of labs, apparently with good results. I can make it available
to anyone who cares for it. Way back, I actually meant to write a
paper on the use of Ca-buffers in physiology and on the traps one can
fall into doing that. Alas, the manuscript was never completed but
early drafts of various sections are on the diskette. They may make
tedious but instructive reading for those who care to understand what
they are doing when they make up and use Ca-buffers. Unfortunately,
all the equations are missing from the electronic version; I couldn't
get them into ASCII format.
All the files take up about 280 Kb of space, including an introductory
readme file. The CABUFFER exe file is about 80 Kb long. The Basic
source code is also provided, so that you can modify it and recompile
it with Turbo Basic or Quickbasic. I can send all of this out on
diskette, or better still, see if I can put the files into a public
directory on our VAX from which you can download them via anonymous
ftp. I will have to talk to our system administrator about this.
I have little time to support this program. Also, if you use it, you
do so at your own risk. But I believe that its use is easy and
self-explanatory, and I also think that it is largely bug-free. In
absolutely critical applications you should always rely on using
carefully calibrated Ca-sensitive electrodes (this is a major
undertaking!). Short of that, this program may get you somewhere,
certainly in simple EGTA buffers.
NYU Medical Center
kleinschmidt at mcclb0.med.nyu.edu