Liquid Chromatographic Determination of Mebendazole and its Metabolites, Aminomebendazole and Hydroxymebendazole, in Eel Muscle Tissue

Abstract

An analytical method is presented for liquid chromatographic (LC) determination of mebendazole (MBZ), hydroxymebendazole (MBZ-OH), and aminomebendazole (MBZ-NH2) in eel muscle tissue. Muscle tissue is extracted with ethyl acetate at pH 7.5. After addition of n-hexane, the extract is cleaned up and concentrated on an aminopropyl solid-phase extraction column. The test solutions are analyzed isocratically on a ChromSpher B LC column with acetonitrile-phosphate buffer, pH 6.2, as mobile phase. Limits of detection and quantitation were 0.7 and 1.1 micrograms/kg, respectively, for MBZ-OH; 1.4 and 2.3 micrograms/kg, respectively, for MBZ; and 1.5 and 2.1 micrograms/kg, respectively, for MBZ-NH2- Interand intraday coefficients of variation were 3.5 and 3.4%, respectively, for MBZ-OH; 2.5 and 3.1%, respectively, for MBZ; and 5.8 and 4.8%, respectively, for MBZ-NH2. Mean recoveries were 90% for MBZ, 74% for MBZ-NH2, and 92% for MBZ-OH. A linear range of applicability of at least 10-1000 micrograms/kg was found for each analyte. Incurred MBZ-NH2 (181.3 micrograms/kg) was identified in eel muscle tissue apart from MBZ (23.7 micrograms/kg) after 48 h exposure in a treatment bath containing MBZ at 1 mg/L.