As published in:
Schoenmakers et al. 1992 CHELATOR: An improved method for computing metal ion concentrations in physiological solutions. Biotechniques 12 870-879.
Chelator calculates a number of chemical equilibria in solutions containing one or more metals, organic chelating compounds and pH buffers. The program automatically recalculates metal-chelator stability constants for effects of ionic strength, temperature, and pH. All ion activities are converted to their respective concentrations using the activity coefficient derived for the ionic strength. Where possible, temperature effects are calculated by Van 't Hoff's Isochore. A detailed description of the methods used can be found in Biotechniques.
The program still is available in its version 1.0. Unfortunately, since I now work in a quite different branch of research and am no longer employed by the University of Nijmegen, I cannot spend any more time on its development or support. If you require a more up-to-date program, you could consider MaxChelator by Chris Patton (more info at the MaxChelator Homepage).
By clicking on the left you can view a full copy of the text of the small manual that I used to send out together with a Chelator diskette. I hope that those notes will help you to understand the program's quirks, and that it will turn out to be a useful program for you. The program itself can be downloaded by clicking on the appropriate link on the right. Packchel.exe (72.6 KB) is a single executable file. Put it in an empty subdirectory on your harddisk and run it. It will unpack into all the files necessary to use Chelator. Once Chelator seems to work as it should, you can safely delete packchel.exe. By now you will have gathered that Chelator should be run on 'Wintel' computers in the old-fashioned MS-DOS environment.
One word of warning: do not save new data files with a name starting with CHEL. Chelator checks for the existence of such files and, if such files exist with a date newer than the original one of Chelator, will abort with no warning....
Please note that not a single computer program will point out exactly what is going on in your solutions; it can only approximate it as much as possible. Select the stability constants most appropriate for your experimental conditions, and double-check them in books like Martell and Smith's Critical Stability Constants series. Keep an eye on the buffering capacity of your media so that you are still working with a safety margin and, finally, try to validate the calculations by a calibration with e.g. a calcium-selective electrode.
All the best,