Fluorimetric determination of the enantiomers of vigabatrin, an anti-epileptic drug, by reversed-phase HPLC with a novel diastereomer derivatisation reagent.

Herein, determination of an anti-epileptic drug, (±)-vigabatrin (VB), was performed by reversed-phase HPLC with fluorimetric detection using a newly designed and synthesised fluorescence derivatisation reagent, 2,5-dioxopyrrolidin-1-yl (4-(((2-nitrophenyl) sulfonyl)oxy)-6-(3-oxomorpholino)quinoline-2-carbonyl)prolinate (Ns-MOK-(R)- or (S)-Pro-OSu). During the derivatisation of VB with Ns-MOK-(R)-Pro-OSu at 60°C, the nosyl (Ns) group, which was introduced to protect a phenolic hydroxy group, was released within 30 min to produce MOK-(R)-Pro-VB, which was detected fluorimetrically at 448 nm with an excitation wavelength of 333 nm. The VB enantiomers can be separated on an octadecylsilica (ODS) column with a resolution value of 14.8, because Ns-MOK-(R)-Pro-OSu bears an optically active D-proline structure. A complete separation of MOK-Pro-(R)- and -(S)-VB enantiomers was achieved on the ODS column within 40 min using stepwise gradient elution, and the detection limits were approximately 0.37 and 0.80 pmol on the column, respectively. The proposed HPLC with fluorimetric detection method was successfully used for determining VB enantiomers in VB-spiked human serum following solid-phase extraction with an anion-exchange cartridge.