CHIRACEL OD-R (a cellulose carbamate) and CHIRACEL OJ-R (a cellulose ester) were used as stationary phases to separate the individual enantiomers. The enantiomers of the DBD–Pro were well separated on the CHIRACEL OD-R column. However, the DBD–Met enantiomers could not be separated on the CHIRACEL OD-R column but were well separated on the CHIRACEL OJ- R column as were the DBD–Ate isomers. The separation of the DBD–Met and DBD–Ate isomers are shown in figure 49 (chromatogram A, DBD–Met and chromatogram B, DBD–Ate). Each enantiomeric pair represents 50 pmol of the original drug. The separation was carried out on the CHIRACEL OJ-R column (15 cm long, 4.6 mm I.D., packed with particles 5 mm in diameter coated with the cellulose ester. The mobile phase used for the separation of DBD–Met was methanol/acetonitrile : 90/10 v/v, at a flow rate of 0.5 ml/min., the separation ratio was 1.33. The mobile phase used for the separation of DBD–Ate was methanol, also at a flow rate of 0.5 ml/min., the separation ratio being 1.53. The excitation wavelength was 450 nm and the emission wavelength was 560 nm. The fluorescent derivatives were found to be stable at 4˚C for over 1 week.