Simultaneous Determination of the Cis-Isomer and L-Isomer in Nateglinide by HPLC

The sample (25 mg) was dissolved and the solution was diluted to 25 mL with a mixed solution of hexane-ethanol-trifluoroacetate (80+20+0.1). Chromatographic separation was achieved on a Chiralpak IG column (250 mm×4.6 mm, 5 μm), with a mixed solution of hexane-ethanol-trifluoroacetate (80+20+0.1) as mobile phase, at a fow rate of 0.8 mL·min^-1. Diode array detector was used for determination at wavelength of 210 nm. Linear relationships were found between peak areas and mass concentraions of cis-isomer and L-isomer in the ranges of 0.024-4.392, 0.050-4.040 mg·L^-1, respectively, with detecion limits (3S/N) of 0.008, 0.015 mg·L^-1 respectively. Values of recovery obtained by standard additon method were in the range of 94.1%-99.3%, 100%-104%, respectively, and RSDs (n=6) were less than 5.0%.