Simultaneous LC/ESI-MS separation method for the enantioseparation of some new anticonvulsant drugs

A sensitive and specific method for the simultaneous determination of the enantiomeric purity of 2,6-dimethylphenoxyacetyl derivatives as trans or cis racemic and enantiomeric forms with 2- or 4-aminocyclohexanol moiety (1, 2, 3, 6) and their amine analogs (8, 9) was developed. The compounds studied are known for their anticonvulsant activity and the most interesting pharmacological results were those for (±)-trans-2-(2,6-dimethylphenoxy)-N-(2-hydroxycyclohexyl)acetamide (1) as well as (±)-trans-2-[(2,6-dimethylphenoxy)ethyl]aminocyclohexanol (8). The analytical method for determining the enantiomeric purity of the compounds studied is based on direct separation of the analytes using a chiral stationary phase (Chiralpak AS column). The mass spectrometric analysis was done on a coupled liquid chromatograph-mass spectrometer system with an electrospray ionization source (LC/ESI-MS). For the compounds 1, 8, and 9, the method allows an excellent separation of enantiomers, with a resolution higher than 3.2, and a tailing factor of less than 1.67 with a final enantiomer purity better than 97.5%.