Please check and be sure that a pH of 8 is appropriate, seems a bit too alkaline for neurotransmitter stock.

Try to contact Prof. Dr. Tao, Nongjian (Oxidation of Neurotransmitters on the Molecular Scale) 

Hi Giuseppe,

I am no chemist but what I can tell you is that when performing e/phys experiments with the transmitters you mentioned, it is quite common to add ascorbate to the ACSF to prevent oxidation.

Hope that helps!

Marcin

Hi Giuseppe

I agree; ascorbate is useful to reduce oxidation. Noradrenaline HCl solution at pH 8 degrades quite quickly at room temperature and in our experience doesn't fare much better at 4C. Noradrenaline tartrate is much more resilient. If it's possible within your protocol, it might be best to keep a fairly acidic stock solution frozen, and thaw it and adjust the pH immediately before use

Best wishes

Chris

Yes. Christopher is right.

We usually keep 10 mM stock solutions of these neurotransmitters in 0.4M PCA (that is acidic) but you can keep it at -70C for 15 months)

for 100ml of PCA solution:

Perchloric Acid (PCA)            3,44ml

Na2 S2O2                     0,1g

EDTA             0,05g

Thank you all.

Your answers were a great help, I'll test it.

Thank you so much!