HPLC OF (±)-FENFLURAMINE AND PHENTERMINE IN PLASMA AFTER DERIVATIZATION WITH DANSYL CHLORIDE

Abstract

A high-performance liquid chromatographic method is described for the simultaneous determination of the dansyl derivatives of (±)-fenfluramine (Fen) and phentermine (Phen) in addition to four other sympathomimetic amines, namely, norephedrine (NE), ephedrine (E), 2-phenylethylamine (2-PEA), and 4-bromo-2,5-dimethoxyphenethylamine (2-CB), using fluoxetine (FLX) as an internal standard. The separation was performed on a reversed-phase C₁₈ column, using a gradient system and fluorescence detection. The dansylation conditions were examined and the optimum derivatization was obtained at pH 9.0 with 4.7 mM dansyl chloride concentration. A preliminary study for the simultaneous determination of the dansyl derivatives in spiked human plasma was performed. The derivatives were well separated within 45 min and showed good linearities from 0.005 to 2μM for E, Phen, and Fen, from 0.002 to 0.8 μM for 2-CB, and from 0.025 to 2 μM for NE and 2-PEA with detection limits ranging from 16 to 255 fmol on the column. Extraction recovery of the compounds was greater than 90%. The applicability of the method was studied in rat plasma following an intraperitoneal administration of Fen and Phen.

Acknowledgments