Simultaneous Determination of Five Polyether Ionophores Using Liquid Chromatography with One-step Fluorescent Derivatization

We present a selective method for simultaneous determination of five polyether ionophores such as salinomycin (SAL), monensin (MON), narasin (NAR), semduramicin (SEM) and lasalocid (LAS) in aquatic samples using a liquid chromatography with one-step fluorescent derivatization of 2-(4-hydrazinocarbonyl-phenyl) 4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride hydrochloride (DIB-Cl). Fluorescent one-step derivatization for SAL, MON, NAR and SEM using HCPI and for LAS using DIB-Cl was monitored by an LC/fluorescence detector (E-x, 340 nm; E-m 465 nm). Chromatographic separation was performed on a TSK-GEL ODS-120T (4.6 x 150 mm, 3 mu m) column using a mobile phase of 0.1% formic acid in acetonitrile and 0.5 mM ammonium formate in water (70/30, v/v). The limits of detections were 0.01 mu g/mL (50 pg) for LAS, 0.05 mu g/mL (250 pg) for SAL, NAR and SEM, and 0.1 mu g/mL (500 pg) for MON, respectively. The recoveries for water samples were indicated to be the range of 79.6 +/- 6.4 - 99.0 +/- 4.4% with associated precision values (between-day for 3 days) for repeatability. Based on solid-phase extraction, the limit of quantitation values indicated 0.1 ng/mL for SAL, MON, NAR and SEM, and 0.01 ng/mL for LAS in water samples.