Simultaneous determination of furosemide and amiloride in plasma using high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method using fluorescence detection for the simultaneous determination of furosemide and amiloride is described. The chromatographic system is based on reversed-phase ion-pair chromatography with sodium dodecylsulphate as ion-pairing agent. The same counter-ion is used for the ion-pair liquid-liquid extraction to ethyl acetate. The minimum detectable concentration amounts to 0.3 ng of furosemide and 0.03 ng of amiloride per ml of plasma. The applicability of the method is demonstrated by the analysis of plasma samples taken from volunteers receiving both drugs.