[IS300bklyn]

I can't seem to determine what type of amino acid these both graphs are, both graphs are titrated from the same unknown.
Thanks

[Babcock_Hall]

The two sets of two pKa values are different.  I don't see how this can be the same amino acid.

[fledarmus]

Can you limit your choices? How many acidic protons and how many basic sites do you have? What sort of groups do your pK measurements suggest?

[IS300bklyn]

I revised the graph but i still couldn't determine which amino acid is this?!??!?

[Borek]

Explaining what you did won't hurt.

[IS300bklyn]

The blue curve is what i titrated the unknown amino acid with HCl and the green curve is NaOH.....next to it are the data points. problem is i couldnt make a good match on what kind of unknown amino acid i titrated with. Thanks

[Babcock_Hall]

Color me puzzled.  In looking at your first graphs, I am struck by the fact that the pK_a values seem different from what a typical amino acid with a non-ionizing side chain would have.  For example, pK₁ for alanine is 2.35, and pK₂ is 9.87.  These values vary a little bit from one source to the next, but they don't vary by huge amounts.

[Borek]

There is something wrong with the NaOH curve. Are you sure pH meter was working OK?