Automated Determination of Drugs in Serum by Column-Switching High-Performance Liquid Chromatography III. Separation of Antiarrhythmic Drugs and Metabolite

A fully automated determination of antiarrhythmic drugs and mono-dealkylated metabolite of disopyramide in human serum has been developed by high-performance liquid chromatography (HPLC) with column-switching. TSKprecolumn BSA-ODS and TSKgel ODS-80TM were used as the precolumn and analytical column, respectively. Fifty μl of serum sample was directly injected onto the precolumn. After washing out the serum proteins from the column by potassium phosphate buffer (30 mmol/l, pH 5.4), the drugs adsorbed on the column were introduced to the analytical column by switching the columnconnection. The drugs were eluted with a step-gradient procedure of acetonitrile/potassium phosphate buffer (30 mmol/l, pH 5.4) both containing sodium 1-heptanesulfonate (500 mg/l), 15/85 by vol (0 to 8 min) to 30/70 by vol (8 to 22 min) at a flow rate of 1.0 ml/min. The effluent was monitored at 210 nm, Analytical recovery (94 to 102%), reproducibility (c.v. less than 3%, withinrun) and linearity indicate that this method is suitable for the therapeutic drug monitoring in clinical laboratories.