Determination of raclopride in human plasma by on-column focusing packed capillary liquid chromatography-electrospray ionisation mass spectrometry

A packed capillary liquid chromatography-electrospray ionisation mass spect rometry method was developed for the quantitative determination of raclopri de in human plasma samples. Plasma samples containing the drug and its isot opically substituted analogue (H-2(3))raclopride as internal standard were extracted on solid-phase extraction discs, evaporated and reconstituted in a solvent with less elution strength than the mobile phase. Packed capillar y columns of 100 mm X 500 mum I.D. were used to obtain high mass sensitivit y in the analysis and large volume injections (20 mul) were performed with analyte enrichment on top of the column. The assay exhibited satisfactory a ccuracy and precision over the concentration range of 0.2-15 nM (70-5200 pg /ml) with a limit of quantification of 0.2 nM. Raclopride in plasma was det ermined after intravenous injection in a positron emission tomography study performed in the tracer dose range. (C) 2000 Elsevier Science B.V. All rig hts reserved.