“…One of the first to recognize the advantages of N-substituted esters of amino acids as derivatives for gas chromatography was Youngs (38), who in 1959 reported that chromatographic peaks had been obtained for the N-acetyl n-butyl esters of glycine, alanine, valine, leucine, isoleucine, and proline. Johnson et al (15,16) investigated the preparation and gas-chromatographic separation of the N-acetyl n-amyl esters. Chromatographic peaks were obtained for the derivatives of 36 amino acids, including 18 of the common protein amino acids, but difficulties were experienced with tryptophan, histidine, cystine, and arginine.…”