Page 220 - Chiral Separation Techniques

198 7 Chiral Derivatization Chromatography

Fig. 7-15. Type III: Increase in selectivity.

7.2.3 Type III: Increase in Selectivity

Derivatization of a racemic compound with an achiral group may play an important
role in the analysis of a chiral compound (Fig. 7-15). In the case of substances with
low or no UV-activity, the compounds can be rendered detectable by introducing an
UV-absorbing or fluorescent group. If the racemate itself shows selectivity on a chi-
ral stationary phase (CSP), this method can be applied to reduce the limit of detec-
tion. Examples have been reported in the literature, especially for the derivatization
of amino acids which are difficult to detect using UV detection. Different derivati-
zation strategies can be applied (Fig. 7-16).

Fig. 7-16. Achiral derivatization of amino acids.