Application of 2D-fluorescence spectroscopy for on-line monitoring of pseudoenantiomeric transformations in supercritical carbon dioxide systems.

2D-Fluorescence spectroscopy has been shown to be effective for the on-line monitoring of spectroscopic detectable substrates L-phenylalanine-7-amido-4-methylcoumarine (L-PheAMC) and D-phenylalanine-7-amido-4-trifluoromethylcoumarine (D-PheAFC) in supercritical carbon dioxide. Earlier investigations with the coumarine substrates in watery and organic phases showed their potential for on-line enantiomeric evaluations of enzymatic reactions in different reaction media. The solubility of the different substrates and their fluorescence maximums were investigated in SCCO2. The sole hydrolyzations of L-PheAMC and D-PheAFC with alpha-chymotrypsin and the esterase from porcine liver were tracked on-line in the supercritical medium; however, different solubility characteristics of the methyl- and trifluoromethyl-substituted coumarins influence the simultaneous detection of the L- and D-substrate within the applied high-pressure reactor system.