title: Determination of torasemide by fluorescence quenching method with some dihalogenated fluorescein dyes as probes.
abstract: A novel fluorescence quenching method for the determination of torasemide (TOR) with some dihalogenated fluorescein dyes as fluorescence probes was developed. In acidulous medium, TOR could interact with some dihalogenated fluorescein dyes such as dichlorofluorescein (DCF), dibromofluorescein (DBF) and diiodofluorescein (DIF) to form binary complexes, which could lead to fluorescence quenching of above dihalogenated fluorescein dyes. The maximum fluorescence emission wavelengths were located at 532 nm (TOR-DCF), 535 nm (TOR-DBF) and 554 nm (TOR-DIF). The relative fluorescence intensities (ΔF=F0-F) were proportional to the concentration of TOR in certain ranges. The detection limits were 4.8 ng mL(-1) for TOR-DCF system, 9.8 ng mL(-1) for TOR-DBF system and 35.1 ng mL(-1) for TOR-DIF system. The optimum reaction conditions, influencing factors were studied; and the effect of coexisting substances was investigated owing to the highest sensitivity of TOR-DCF system. In addition, the reaction mechanism, composition and structure of the complex were discussed by quantum chemical calculation and Job's method. The fluorescence quenching of dihalogenated fluorescein dyes by TOR was a static quenching process judging from the effect of temperature and the Stern-Volmer plots. The method was satisfactorily applied to the determination of TOR in tablets and human urine samples.
authors.affiliation: Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Cui
authors.forename: Shaopu
authors.initials: S
authors.lastname: Liu
authors.forename: Zhongfang
authors.initials: Z
authors.lastname: Liu
authors.forename: Yuanfang
authors.initials: Y
authors.lastname: Li
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Hu
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
mesh_terms: D000959:Antihypertensive Agents / Q000032:analysis / Q000652:urine*; D004232:Diuretics / Q000032:analysis / Q000652:urine*; D019793:Fluorescein / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D054879:Halogenation; D006801:Humans; D057230:Limit of Detection; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013449:Sulfonamides / Q000032:analysis / Q000652:urine*; D000077786:Torsemide
chemical_list: D000959:Antihypertensive Agents; D004232:Diuretics; D005456:Fluorescent Dyes; D013449:Sulfonamides; D019793:Fluorescein; D000077786:Torsemide
keywords: Dibromofluorescein; Dichlorofluorescein; Diiodofluorescein; Fluorescence quenching; Torasemide