Solid-phase extraction and ion-pair reversed-phase HPLC of isometamidium in bovine serum and tissues

An analytical method has been developed for the determination of isometamidium in bovine serum and tissues. Samples were enzymatically hydrolysed and cleaned up on a solid-phase system (C8 Bond Elut column). The drug was chromatographed by an ion-pair reversed-phase technique using heptane sulphonate as a pairing-ion and triethylamine as a counter-ion reagent. Detection was by fluorescence at 593 nm (excitation = 380 nm). The method is more sensitive and specific than existing methods and it is currently being used in evaluating the pharmacokinetics of isometamidium in cattle.