Abstract
Two analytical methods, High Performance Liquid Chromatography (HPLC) o-phthaldialdehyde (OPA) derivatization / Fluorometry and Ion Chromatography (IC) / Conductimetry, have been established for qualitative and quantitative analysis of the possible nitrogen-containing photoproduct compounds (amines and ammonium ions) from photolysis of copper(II) – amino acids complexes in aqueous soultion without oxygen under monochromatic radiation at 313 nm. Due to the ligand to metal charge transfer (LMCT) during the irradiation, copper(II) was reduced to copper(I) and the ligand was oxidized and decomposed to final products. While testing different ligands including α-alanine, leucine, isoleucine, phenylalanine, valine, methionine, proline and arginine with copper(II), photoproduction of ethylamine instead of NH4+ is only observed in Cu(II)-β-alanine complex system. The quantum yields of ammonium ion (ΦNH3) as a major nitrogen-containing photoproduct is just the half of the quantum yields of copper(I) (ΦCu(I)) in the copper(II)-α-amino acid complex system. The experimental results show that the value ΦCu(I) /ΦNH3 ratio still remains the same while alternating the pH, concentration of metal, and ligand in Cu(II)-α-alanine complexes. According to the results from the study, a possible pathway for the decomposition of the amino acids in the copper(II)-α-amino acid complex system is proposed.