major microspecies calculation

User c2d41a4dbe

26-11-2008 10:18:35

Dear support,

I have noticed a disaggreement between the major microspecies calculation and the microspecies distribution (ChemAxon 5.0.04, with marvinView or cxcalc).

For example, for the molecule attached, the major microspecie found at pH7.4 is an anionic form (N-), whereas the microspecies distribution shows that the neutral form is dominant between pH5 and pH11, and that the anionic form is only dominant when pH is more than 11.

Which tool gives the right answer?

Moreover, I have noticed that older versions of ChemAxon (3.2.6 and 3.1.6) give the neutral form when you calculate the major microspecie at pH 7.4.


Loraine Brillet

OS : Linux, Centos release 5

User 851ac690a0

27-11-2008 18:36:41


This was a bug. Meanwhile we fixed this problem.

You can try the fixed version here:

Neutral form seems to be dominant at pH=7.4 according to the present calculations.