Liquid Chromatographic Determination of a Substituted Benzamide in Biological Fluids Using Preconcentration and Post-Column Extraction

Abstract A sensitive and selective semi-automated method has been developed for the determination of Remoxipride in biological fluids. The chromatographic behaviour of the basic drug is strongly improved by treatment of the C-18 bonded column with hexadecyltrimethylammonium bromide. The use of disposable precolumns permits the direct injection of 1:1 (v/v) diluted plasma or 1:9 (v/v) diluted urine. For detection, a post-column ion-pair extraction with the strongly fluorescent 9,10-dimethoxyanthracene-2-sulphonate was used. A new sandwich type phase separator helped to keep band broadening very low. The calibration curves of Remoxipride in plasma and urine show correlation coefficients of 0.9999 over at least two orders of magnitude. Detection limits are 1 ng/ml in plasma and 15 ng/ml in urine. The recovery of Remoxipride from spiked plasma and urine is 88% and 76%, respectively. The reproducibility, based on peak height measurements, for determinations in plasma (200 ng/ml) was 3.5% (RSD) within one seria...