AUTOMATED-ANALYSIS OF OXOLINIC ACID AND FLUMEQUINE IN SALMON WHOLE-BLOOD AND PLASMA USING DIALYSIS COMBINED WITH TRACE ENRICHMENT AS ONLINE SAMPLE PREPARATION FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The use of dialysis as sample clean-up for high-performance liquid chromatography makes fully automated determination of drugs in whole blood and plasma possible. High recoveries of the analytes oxolinic acid and flumequine and the internal standard nalidixic acid are obtained after a short time of dialysis (7.3 min). The dilute dialysates are enriched on a small column packed with polystyrene. When dialysis is discontinued, the analytes are eluted by mobile phase to the analytical column. With UV detection the limit of detection was 50 ng/ml for both oxolinic acid and flumequine. Validation showed good precision and accuracy and good correlation between determinations in plasma and whole blood.