structurally informative fragmentation patterns of the cysteine- and n-acetylcysteine derivatives were obtained when their methyl esters were subjected to analysis by direct insertion chemical ionization ( ch4 ) mass spectrometry , although field desorption and liquid secondary ion mass spectrometric techniques were required in order to obtain satisfactory spectral data for derivatives of the glutathione adduct .
C0010654
cysteine
C0001047
n-acetylcysteine