MAXC DOWNLOADS

REFERENCES    ESSENTIAL UNDERSTANDINGS   DISCLAIMER  

NOTE: No software program is as good as actually measuring the free metal concentrations with a macroelectrode or fluorescent method. See reference #9
 

PLEASE add either of these URLs to your papers:
http://www.stanford.edu/~cpatton/maxc.html       or      http://maxchelator.stanford.edu
 

     Donald Bers' Excel Spreadsheets see references
 

The most accurate software program for determining free metal concentrations currently is

    Theo Schoenmakers' program Chelator [DOS] reference #8

His program takes into account far more species of ions that the Max Chelator series do.
 
Newest Versions - web versions that are easy to change constants in
Slight differences in answers are the result of rounding errors in calculations
  Single Chelator Metal Calculators
     MgATP - Free, Total, Bound and Total ATP, constants from NIST database #46 v8 (25°C, 0.1N) 1
     MgATP - Free, Total, Bound and Total ATP, constants from 'Chelator' program (37°C, 0.165N) 2
     CaEGTA - Free, Total, Bound and Total EGTA, constants from NIST database #46 v8 (25°C, 0.1N) 1
     CaEGTA - Free, Total, Bound and Total EGTA, constants from 'Chelator' program (37°C, 0.165N) 2
  Two Chelator, two metal calculators
     CaMgATPEGTA - Free & Total, constants from NIST database #46 v8 (25°C, 0.1N) 1
     CaMgATPEGTA - Free & Total, constants from 'Chelator' program (37°C, 0.165N) 2
 
  EXPERIMENTAL: Two Chelator, two metal calculators w/ pH plot [does not work with IE browser]
     CaMgATPEGTA - Free & Total, constants from NIST database #46 v8 (25°C, 0.1N) 1
     CaMgATPEGTA - Free & Total, constants from 'Chelator' program (37°C, 0.165N) 2
 
If you are unable to deal with the source code for the above pages I will endeavor to create a version with whatever metals/chelators/constants you need, assuming constants are available.
 
Older Versions and non Maxc programs -
 
     Older Web Maxc versions Standard and Extended and the Lite version [Ca,Mg, ATP, EGTA)
        constants from Bers and from NIST database, adapted to 20°C, 0.1N
 
     Calculator for pH buffers WEBBUFCALC - Good buffer [ion] contrib
 
      1 Windows Maxc program winmaxc32.zip v2.51 constants from NIST database, adapted to 20°C, 0.1N
 
      2 Theo Schoenmakers' program Chelator [DOS] reference #8
 
     Brook & Storey's program Bound & Determined [DOS] reference #2
 

 
  Latest Reference to the MAXC programs is:

Patton, Thompson and Epel.
"Some precautions in using chelators to buffer metals in biological solutions."
Cell Calcium. 35/5 pp. 427-431, 2004.
 

FAQ: Why do different programs give different results to the same calculation?

Answer: Every programmer has to make assumptions about how all of this works and what are the "best" constants to use [definitely no agreement on either issue]. No programmer starts out to make an invalid program. The results most likely do fit the observations made in their own lab. The problems come in when the programs are extended beyond experience into new situations [like yours]. A classic case of a person with two watches does not know what time it is.

Consider all of these programs to be a work in progress. It is VERY important that you always report what program you used, including version information.

Constants come from two sources: Martell & Smith Critical Stability Constants [ref#6] in the updated database from NIST and from constants determined in individual labs.

Disclaimer:

My degree, a B.A., is in Biology and Photography, NOT physical chemistry.[I was top of my class in Analytical Chemistry as an undergraduate, but that still does not qualify me as an expert.] I work as a professional technician at Stanford University's Hopkins Marine Station [30+ years]   I have been working with these equations and ideas for over twenty five years. I became interesting in doing these programs when they were needed for my work with Professor David Epel, also a biologist. I saw a need for an easier to use program than what was available at the time. By working with many experts in the field and a lot of cross checking and validation, the programs came to be.

However, I am not an expert. There are likely to be errors in understanding and possibly code execution. Mistakes have been found in the past. If anything, these programs are really a community effort. As people ask questions and answers are found they are incorporated into these pages and code.

I am willing to attempt to answer any questions you have, but if it is beyond my abilities I will readily admit so.

Chris Patton
cpatton@stanford.edu