title: Miniaturized graphite sensors doped with metal-bathophenanthroline complexes for the selective potentiometric determination of uric acid in biological fluids.
abstract: Miniaturized poly(vinyl chloride) matrix membrane sensors in an all-solid-state graphite support, responsive to urate anion, were developed. The membranes incorporate lipophilic ion-pair complexes of urate anion with ruthenium(III), iron(II), nickel(II) and copper(I) bathophenanthroline (4,7-diphenyl-1,10-phenanthroline) counter cations. The sensors demonstrate a near-Nernstian response to urate over the concentration range 1 x 10(-2)-1 x 10(-5) mol l-1 and have micromolar detection limits and good selectivity properties. The response is virtually unaffected by pH changes in the range 7-10 and the response times are 5-10 s in aqueous solutions and in human serum and urine samples. A flow injection detector incorporating an iron(II) bathophenanthroline-urate graphite sensor was used for continuous monitoring of uric acid. The minimum detectable concentration was approximately 8 micrograms ml-1 and the sample throughput was approximately 120 h-1. Direct potentiometric determination of uric acid in the static and hydrodynamic modes of operation over the range 15 micrograms ml-1-1.5 mg ml-1 showed average recoveries of 98.7 and 97.8% with RSDs of 0.6 and 0.7%, respectively. Application of the method to the determination of uric acid in human serum and urine gave results that compared favourably with those obtained by the standard spectrophotometric method.
authors.affiliation: Department of Chemistry, Faculty of Science, Ain Shams University, Cairo, Egypt.
authors.forename: S S
authors.initials: SS
authors.lastname: Hassan
authors.forename: N M
authors.initials: NM
authors.lastname: Rizk
mesh_terms: D017022:Flow Injection Analysis; D006108:Graphite; D006801:Humans; D008567:Membranes, Artificial; D008670:Metals; D010618:Phenanthrolines; D011143:Polyvinyl Chloride; D011199:Potentiometry / Q000295:instrumentation / Q000379:methods; D014527:Uric Acid / Q000032:analysis* / Q000097:blood / Q000652:urine
chemical_list: D008567:Membranes, Artificial; D008670:Metals; D010618:Phenanthrolines; D014527:Uric Acid; C006686:bathophenanthroline; D006108:Graphite; D011143:Polyvinyl Chloride