Benita H. Forngren

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 spectrometry method was developed for the quantitative determination of raclopride in human plasma samples. Plasma samples containing the drug and its isotopically substituted analogue (2H3)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 capillary columns of 100 mm x 500 microm I.D. were used to obtain high mass sensitivity in the analysis and large volume injections (20 microl) were performed with analyte enrichment on top of the column. The assay exhibited satisfactory accuracy 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 determined after intravenous injection in a positron emission tomography study performed in the tracer dose range.

Determination of specific radioactivity for 76Br-labeled compounds measuring the ratio between 76Br and 79Br using packed capillary liquid chromatography mass spectrometry

Packed capillary liquid chromatography with electrospray mass spectrometry was used for direct determination of the specific radioactivity by calculation of isotope ratios between the (76)Br- and (79)Br-labeled analogues of N-((3-aminomethyl)benzyl)-4-bromobenzamide. Using 20 microL injections on packed capillary columns, sufficient mass sensitivity was attained for the determination on an injected amount of radioactivity corresponding to approximately 2 MBq (0.3 pmol of the (76)Br isotopic analogue).