QUANTITATIVE-ANALYSIS OF FLUORINATED ETHYLCHLOROFORMATE DERIVATIVES OF PROTEIN AMINO-ACIDS AND HYDROLYSIS PRODUCTS OF SMALL PEPTIDES USING CHEMICAL-IONIZATION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

The derivatization and extraction efficiencies of 16 protein amino aci ds were investigated using trifluoroethanol + ethylchloroformate + pyr idine as the derivatization reagents and chloroform as the solvent. Th e derivatization efficiencies ranged from 90% to 99% for all the amino acids studied except aspartic acid (79%). The extraction efficiencies of the derivatized amino acids using chloroform were close to 100%. I n addition, the detection limits and linear dynamic ranges of trifluor oethanol ethylchloroformate (TFE-ECF) derivatives of these amino acids were studied using positive-ion chemical ionization gas chromatograph y-mass spectrometry (GC-MS). The detection limits of the protein amino acids were mostly in the low femtomole range. The linear dynamic rang es of these amino acids were in the range of zero to three orders of m agnitude. The GC-MS analysis of the derivatized amino acids was applie d to the hydrolysis products of Equal, a sugar substitute containing a spartame and diprotin B, a tripeptide. The results demonstrate that th e TFE-ECF derivatization of the hydrolysis products of small peptides followed by GC-MS analysis can be used for the identification of their amino acid composition (except arginine) and for their complete amino acid analysis.