title: Non-protected fluid room-temperature phosphorimetric procedure for the direct determination of naftopidil in biological fluids.
abstract: Non-protected fluid room temperature phosphorescence, NPRTP, has been applied to the determination of naftopidil in biological fluids. The proposed method is based on obtaining a phosphorescence signal from naftopidil using potassium iodide as heavy atom perturber and sodium sulfite as a deoxygenating reagent without a protected medium. Optimized conditions for the determination were 1.4 mol L= KI, 5.0 x l0(-3) mol L(-1) sodium sulfite, pH 6.5 (adjusted with sodium hydrogen phosphate-dihydrogen phosphate buffer solution, 5.0 x 10(-2) mol L(-1). The delay time, gate time, and time between flashes were 70 micros, 400 micros, and 5 ms, respectively. The maximum phosphorescence signal appeared instantly and the intensity was measured at lambda(ex)=287 nm and lambda(em)=525 nm. The response obtained was linearly dependent on concentration in the range 50 to 600 ng mL(-1). The detection limit, according to error-propagation theory, was 7.93 ng mL(-1) and the detection limit as proposed by Clayton was 11.12 ng mL(-1). The repeatability was studied by using ten solutions of 400 ng mL(-1) naftopidil; if the theory of error propagation is assumed the relative error is 0.88%. The standard deviation of replicates was found to be 3.5 ng mL(-1). This method was successfully applied to the analysis of naftopidil in human serum and urine with recoveries of 104.0 +/- 0.6% for serum and 106.0 +/- 1.0% for urine.
authors.affiliation: Department of Analytical Chemistry and Foods Technology, University of Castilla-La Mancha, Ciudad Real, Spain. jamurill@qata-cr.uclm.es
authors.forename: J A
authors.initials: JA
authors.lastname: Murillo Pulgarín
authors.forename: A
authors.initials: A
authors.lastname: Alañón Molina
authors.forename: M T
authors.initials: MT
authors.lastname: Alañón Pardo
mesh_terms: D000959:Antihypertensive Agents / Q000032:analysis* / Q000097:blood / Q000652:urine; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008163:Luminescent Measurements; D009281:Naphthalenes / Q000032:analysis* / Q000097:blood / Q000652:urine; D010879:Piperazines / Q000032:analysis* / Q000097:blood / Q000652:urine; D011193:Potassium Iodide / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods / Q000592:standards; D013696:Temperature
chemical_list: D000959:Antihypertensive Agents; D009281:Naphthalenes; D010879:Piperazines; D011193:Potassium Iodide; C064357:naftopidil