Analytical Sciences

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

Koichi INOUE,* Yukiko MIURA,* Misato SUZUKI,* Naoya KISHIKAWA,** Tomoaki HINO,* Naotaka KURODA,** and Hisao OKA*

*Department of Physical and Analytical Chemistry, School of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama, Nagoya 463-8521, Japan
**Graduate School of Biomedical Sciences, Course of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan

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 × 150 mm, 3 μm) 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 μg/mL (50 pg) for LAS, 0.05 μg/mL (250 pg) for SAL, NAR and SEM, and 0.1 μg/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.

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