title: Determination of piretanide and furosemide in pharmaceuticals and human urine by high-performance liquid chromatography with amperometric detection.
abstract: A high-performance liquid chromatographic method with electrochemical detection (ED) has been developed for the determination of two diuretics: 4-phenoxy-3-(1-pyrrolidinyl)-5-sulfamoylbenzoic acid (piretanide) and 4-chloro-2-furfurylamino-5-sulfamoylbenzoic acid (furosemide). The chromatographic separation was performed on a mu Bondapak C18 column with a mobile phase of acetonitrile-water (40:60) containing 5 mM KH2PO4/K2HPO4 and with a flow-rate of 1 ml/min (69 bar). The temperature was optimized at 30 +/- 0.2 degrees C. The amperometric detector equipped with a glassy carbon electrode was operated at +1200 mV versus Ag/AgCl in the direct current mode. The method was applied to the determination of these compounds in two concentration ranges (ppm and ppb), obtaining a reproducibility in terms of relative standard deviations lower than 1% for within-day and 4% for day-to-day and determination limits of 15 ppb for both compounds. Recoveries greater than 90% were obtained for spiked urine samples, using a liquid-liquid extraction method in the sample clean-up procedure. The LC-ED method was applied to commercially available pharmaceuticals (Seguril, furosemide 40 mg, and Perbilén, piretanide 6 mg) and urine samples obtained from healthy volunteers and hypertensive patients.
authors.affiliation: Departamento de Química Analítica, Universidad del País Vasco, Bilbao, Spain.
authors.forename: M B
authors.initials: MB
authors.lastname: Barroso
authors.forename: R M
authors.initials: RM
authors.lastname: Jiménez
authors.forename: R M
authors.initials: RM
authors.lastname: Alonso
authors.forename: E
authors.initials: E
authors.lastname: Ortiz
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004232:Diuretics / Q000032:analysis* / Q000737:chemistry / Q000652:urine; D004563:Electrochemistry; D005665:Furosemide / Q000032:analysis* / Q000737:chemistry / Q000652:urine; D006801:Humans; D015203:Reproducibility of Results; D013449:Sulfonamides / Q000032:analysis* / Q000737:chemistry / Q000652:urine
chemical_list: D004232:Diuretics; D013449:Sulfonamides; D005665:Furosemide; C015451:piretanide