**4.2. Determination of the enantiomeric excess (***ee***) of ATH**

Typical instrumental method for determination of optical purity at products of reaction is gas or liquid chromatography, using columns with chiral stationary phase. However, these columns are relatively expensive. Another disadvantage is that these columns is higher sensitivity, which manifest itself during GC analysis by lower temperature limit and at LC analysis by impossible analysis of any chemicals or are limited by certain pH. Hence, alternative methods using derivatization or chiral solvatation of the product are expedient.
