Simple question about aminoacid stability in solution

[dragosb]

Hi everyone,

I have just a simple question to ask, if someone can give me an answer.
I would like to know what the stability of aminoacids in a water solution is.
I am trying to measure the concentration of an AA in plasma and I need to prepare a calibration solution of the aminoacid (the aminoacid is a drug allready disolved in water), two or three different concentrations but I do not know for how long I will be able to use them as calibrators for my method.
Please help me if you have any experince with that.

Thank you

[Vlad Orlovsky]

Amino acids should be stable for the duration of your experiments, you might want to dissolve it in ACN/water vs. just water. Some of the amino acids, which contain hydroxy and carboxyl group might self-condense to form a ring or polymerize.

[Andy Alpert]

I've worked for weeks with aqueous solutions of amino acids without observing any deterioration, with the exception of glutamine. At low pH, it will deamidate and form pyroglutamic acid, with a half life of about 12 hours. If you just plan to use plain water, though, then there shouldn't be a problem.

[dragosb]

Thank you for your responses.

I plan to use a Tranexamic acid solution to spike the plasma in order to have my calibration samples.
So this is why I asked for how long I can keep the Tranexamic acid aqueous solution at room temperature.
Let me know what you think about this.

Thanks