Determination of triptonide by cloud point extraction combined with MEKC.

A method has been developed for the determination of triptonide in the traditional Chinese herb Tripterygium wilfordii Hook F. by micellar electrokinetic capillary chromatography combined with cloud point extraction. The analyte was extracted at pH 3.0 by micelles of the nonionic surfactant polyoxyethylene 7,5-octylphenyl ether (Triton X-1 14). A 250-mu L, aliquot from the extracted surfactant-rich phase was diluted to 400 mu L with ethanol to reduce its viscosity before separation by MEKC. Under optimum conditions, an enrichment factor of 25 is obtained and the determination limit of triptonide is found to be 3.15 x 10(-7) mol/L. The proposed method has been successfully applied to the determination of triptonide in T. wilfordii tablet and spiked urine matrix, demonstrating the feasibility and reliability of the proposed method.