this method involves gradient elution of 18 common amino acids on a c18 column using sodium octanesulfonate as an ion-pairing agent , postcolumn derivatization with o-phthalaldehyde and 2-mercaptoethanol ( combined with hypochlorite oxidation for the imino acid proline ) introduced into the main flow stream using sulfonated and aminated hfmrs immersed in the reagent solutions , and fluorometric detection of derivatives ( lambda ex = 340 nm , lambda em = 450 nm ) .
C0020931
imino acid
C0033382
proline