FORMATION AND FRAGMENTATIONS OF ORGANOMETALLIC COMPLEXES INVOLVING ALIPHATIC ALPHA-AMINO-ACIDS AND TRANSITION-METAL CATIONS - A PLASMA DESORPTION MASS-SPECTROMETRY STUDY

Amino acid/transition metal chloride mixtures were studied by plasma desorption mass spectrometry. The six aliphatic alpha-amino acids were considered: glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile) and proline (Pro), together with four transition metal chloride salts: CoCl2, NiCl2, CuCl2, and FeCl2. Mixtures spectra show that MCat(+) complexes are formed where M = amino acid and Cat = Co, Ni, Cu or FeCl. Fragmentations of MCat(+) ions lead to both organometallic and organic ions. Isotopic labelling has allowed to demonstrate some fragmentation mechanisms.