Negative ion chemical ionization (Cl<SUP>-</SUP>) mass spectra of amino acids

Negative ion chemical ionization (Cl-) mass spectra of the commonly occurring amino acids are simple and give information regarding molecular weight by the presence of [M + Cl]- adduct in the case of simple amino acids and [M - H]- in the case of amino acids containing additional polar groups. tert-Butyloxycarbonyl (BOC)-protected di-, tri- and tetrapeptides also given abundant [M + Cl]- ions