Amino acids are mainly detected with florescence detection. To get good resolution of amino acids in HPLC-UV you have to derivatise with pthaldehyde. Details I already answered in ResearchGate. Please search.
thanks for giving me this information, but as you know derivation of amino acids with phethaldehyde need organic medium but I want to work in aqueous solution.
If you need to determine free amino acids, simply dissolve sample in 0.1 M HCl and blend or shake. After that, inject it into LC system after filtration. Chromatography conditions and automatic derivatization are the same.
Article Validation of an HPLC method for the determination of amino ...
You may want to take a look at this paper (acqueous medium and UV detection of aa, amines and ammonium). Hope this help:
Fermentation of sulphite-free white musts with added lysozyme and oenological tannins: Nitrogen consumption and biogenic amines composition of final wines
M.J. Cejudo-Bastante, F. Sonni, F. Chinnici, A. Versari, M.S. Perez-Coello, C. Riponi
LWT - Food Science and Technology 01/2010; DOI:10.1016/j.lwt.2010.02.011
If you don't want to derivatise the aminoacids you can do the analysis directly using a pulse amperometric detector or using Using Evaporative Light Scattering Detection.