Development an ion-pair liquid chromatographic method for determination of sotalol in plasma using a monolithic column

A rapid and sensitive ion-pair HPLC method using a monolithic column and fluorescence detection has been developed for quantification of sotalol in plasma. The assay enables the measurement of sotalol for therapeutic drug monitoring with a minimum quantification limit of 10 ng ml−1. The analytical method involves simple, one-step protein precipitation and no extraction procedure is needed. Sample preparation is fast and the analytical recovery was complete. The separation was carried out in reversed-phase conditions using a Chromolith Performance (RP-18e, 100 mm × 4.6 mm) column at ambient temperature. The mobile phase was 10% acetonitrile, 0.001 M heptane sulfonic acid, 0.02 M sodium dihydrogen phosphate, and distilled water to 100%, adjusted to pH 5.5 at a flow rate of 1.8 ml/min. The excitation wavelength was set at 235 nm, emission at 300 nm. The calibration curve was linear over the concentration range 20-1500 ng ml−1. The coefficients of variation for inter-day and intra-day assay were found to be less than 7%. The method has been applied to the determination of sotalol in plasma from 12 subjects dosed with racemic sotalol.