Highly sensitive isomeric determination of beraprost sodium in plasma using a fluorescent chiral derivatization reagent

(S)-(+)-2-(Anthracene-2,3-dicarboximido)-1-propyl trifluoromethanesulfonate (AP-OTf) was synthesized as a chiral fluorescence derivatization reagent for carboxylic acids. Beraprost sodium (BPS), which is composed of four optical isomers, was derivatized with this reagent, and the derivatives were separated into each isomer by an HPLC using a silica gel column. This method was applied to determine BPS in human plasma. By the method, the determination range of the four isomers of BPS were 6 - 3000 fmol (0.5 - 250 ng/ml) and their detection limits were 3-4 fmol (1.3-1.7 pg, signal-to-noise ratio =3). This method made it possible to detect 0.25-0.33 ng/ml of each isomer of BPS in plasma.