DIRECT RESOLUTION IN SUBCRITICAL AND SUPERCRITICAL-FLUID CHROMATOGRAPHY ON PACKED-COLUMNS CONTAINING TRANS-1,2-DIAMINOCYCLOHEXANE DERIVATIVES AS SELECTORS

Sub- and supercritical fluid chromatography (sub-FC and SFC) are particularly suitable techniques for the direct resolution of enantiomers. This article discusses some of the key salient aspects of sub-FC and SFC in the context by packed analytical and microbore columns using chiral stationary phases containing derivatives of trans-1,2-diaminocyclohexane as selectors. Some examples of the separation of complex mixtures of enantiomers using several columns in series are shown, and the influence of analysis temperature, mobile phase composition and the properties of stationary phases are also examined. To conclude, the high speed of the technique will be used in the study of fast stereodynamic processes (enantiomerization and diastereoisomerization). The results obtained using modern SFC instrumentation and chiral stationary phases, are generally more successful when compared to the corresponding high-performance liquid chromatographic method, and make this technique a practical and attractive alternative for the future.