DETERMINATION OF D-FENFLURAMINE, D-NORFENFLURAMINE AND FLUOXETINE IN PLASMA, BRAIN-TISSUE AND BRAIN MICRODIALYSATE USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AFTER PRECOLUMN DERIVATIZATION WITH DANSYL CHLORIDE

A HPLC method is described for the simultaneous determination of D-fen fluramine (FEN), D-norfenfluramine (NF) and fluoxetine (FLX) using flu orometric detection after precolumn derivatization with dansyl-chlorid e. The method has limits of quantitation of 200 fmol for FEN and NF, 5 00 fmol for FLX in brain microdialysate, and 1 pmol for NF and FEN, an d 2 pmol for FLX in plasma. Brain tissue standards were linear between 5 and 200 pmol/mg for all three compounds. The inter-assay variabilit y (relative standard deviation) was 6.6%, 6.9% and 9.3% for FEN, 4.6%, 3.7% and 7.9% for NF and 10.4%, 4.9% and 12.2% for FLX, for brain mic rodialysate (2 pmol/mu l), plasma (2 pmol/ mu l) and brain tissue (50 pmol/mg), respectively. Intra-assay variability was always lower, typi cally several times lower than inter-assay variability. Extraction rec overy was 108% and 48% for FEN, 105% and 78% for NF and 94% and 45% fo r FLX, in plasma (2 pmol/mu l) and brain tissue (5 pmol/mg), respectiv ely. Due to the stability of the dansyl-chloride derivatives this meth od is well suited for an autoinjector after manual derivatization with dansyl chloride at room temperature for 4 h.