fluoroacetic anhydride. The new phase was then crystallized as white needles (yield 79 % ; m. p. 110-1 12 "C ; elemental analysis, calc.: C 52.45, H 6.88, N 7.59, F 15.56; found: C 52.44, H 6.90, N 7.62, F 15.66; homogeneous on thinlayer chromatography with various solvents and on gas chromatography-mass spectrometry on an SE-30 column).The gas-chromatographic investigations with the new stationary phase were carried out on a Varian 1200-1 gas chromatograph equipped with an FID detector, modified for capillary columns. A stainless steel capillary column (122mx0.508mm) was coated with a 10% solution of cyclohexyl N-TFA-L-a-aminobutyryl-L-a-amibobutyrate in methylene chloride and conditioned in the usual way[2v31. At 120°C with a carrier gas (He) pressure of 1.76 kp/cm2, enantiomeric mixtures of the isopropyl esters of the TFA derivatives of D,L-alanine, D,L-valine, D,Lthreonine, D,L-isoleucine, D,L-leUCine, D,L-serine, D,L-proline, and D,L-aspartic acid could be completely separated, but glycine and L-threonine were not wholly separable.This resolution was achieved, however, at 110°C (Fig. 1). Separation of the higher-boiling isopropyl esters of N-TFAamino acid esters on a 30m capillary column has been previously described by usL2'. I I I I 1 2 3 4 5 6 7 12628.11 t lhl-Fig. 1. Chromatogram of isopropyl esters ofTFA-amino acids on cyclohexyl N-TFA-L-a-aminobutyryl-L-a-aminobutyrate as the stationary phase. Chromatographic conditions: 122 in x 0.508 mm capillary column 110°C isothermal; entry block 190°C, detector temperature 290°C; carrier gas helium at 1.76 kp/cm2.With this new, optically active, stationary phase the more volatile amino acid derivatives can now be separated unambiguously from one another. In this way, 16 of the naturally occurring amino acids can be investigated relatively rapidly (6 h) and with great precision (1 %) to a limiting detection range of 0.1 %. Since, unlike the separation of diastereomers on o p t i c~l l y inactive stationary phases, nonasymmetric reagents were used for derivatization of the amino acids and correction of the results for antipodic impurities is unnecessary.