High-performance liquid chromatographic determination of some amino acids after derivatization with 2-hydroxy-1-naphthaldehyde.

2-Hydroxy-1-naphthaldehyde (HNA) was investigated as a derivatizing reagent for the fluorescence detection of histidine, methionine and tryptophan at 385 and 265 nm. The separation of HNA-derivatized amino acids on a conventional reversed-phase column was achieved in less than 40 min. This method was compared with the reported o-phthaldialdehyde (OPA) method. The procedure was successfully applied to the assay of the pure amino acids in a mixture and their pharmaceutical dosage forms.