Sensitive high-performance liquid chromatographic determination of propranolol in human plasma with ultraviolet detection using column switching combined with ion-pair chromatography

Abstract

High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection is the most widely used method for the determination of drugs in biological fluids. Unfortunately, propranolol (PL), a P-adrenergic blocking agent, shows strong UV absorption only in the short-wavelength region (molar absorptivity at 215 nm is 42 000), which lacks selectivity and is not usually suitable for the sensitive determination of drugs in biological fluids. PL has a native fluorescence, which allows its sensitive and selective detection with a simple pretreatment. Therefore, PL in biological fluids has been mainly determined by HPLC with fluorimetric detection [l-6]. We recently reported that the column-switching technique combined with ion-pair chromatography offers high selectivity and sensitivity for tertiary [ 731 or primary amines [9] whose elution can be delayed by ion-pair formation, even with a poorly selective short-wavelength UV detection. Although fluorimetric detection will be usually the method of choice, we made investigations to show that this technique, preceded by a simple pretreatment, can offer high sensitivity and selectivity for PL, as an example of a secondary amine, in plasma with UV detection and to demonstrate its wide applicability to basic compounds.