Gas chromatography chemical ionization mass spectrometry in amino acid analysis of pyoverdins

The application and advantages of positive chemical ionization with methane [CI(CH4)] for gas chromatography-mass spectrometry (GC-MS) of perfluoroacyl amino acid alkyl esters are discussed. All investigated amino acids show [M+H](+), [M+C2H5](+), and [(M+H)-C3H6](+). By a comparison of the electron ionization (EI) and CI(CH4) mass spectra the analysis of amino acid mixtures by GC-MS will give reliable results also in the case of isomeric compounds or of (partial) decomposition during analysis. (C) 1997 Elsevier Science B.V.