Читать книгу Chemical Analysis - Francis Rouessac - Страница 83

An organic molecular compound, whose formula demonstrates a centre of asymmetry, leads at our scale, i.e. macroscopic, to a mixture of the two possible enantiomers R and S, in equal quantities or not. Their physical properties are identical, but their behaviour regarding polarized light is what distinguishes them, hence the name of optical activity. In space, these two forms cannot be superimposed. One is the mirror image of the other.

The separation of optical isomers is an important application of chromatography. GC optimizes separations more quickly than other chromatographic techniques (see Chapters 4, 5, and 6). Therefore, it holds a privileged spot in this field, even though the selectivity factor for enantiomer pairs remains close to 1.

Two separations methods exist: direct process and indirect process.