title: Electroanalysis and simultaneous determination of 6-thioguanine in the presence of uric acid and folic acid using a modified carbon nanotube paste electrode.
abstract: The present work describes the preparation and characterization of a carbon nanotube paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one (2,7-BF).  This electrode showed an efficient catalytic activity for the electro-oxidation of 6-thioguanine (6-TG), which leads to lowering 6-TG overpotential by more than 610 mV.  Also, the values of catalytic rate constant (k = 2.7 × 10(3) mol(-1) L s(-1)), and diffusion coefficient (D = 2.7 × 10(-5) cm(2) s) were calculated.  In 0.1 M phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of 6-TG, one is 0.06 to 10.0 µmol L(-1) and the other is 10.0 to 160.0 µmol L(-1).  The detection limit (3σ) obtained by differential pulse voltammetry (DPV) was 22.0 nmol L(-1).  DPV was used for simultaneous determination of 6-TG, uric acid (UA) and folic acid (FA) at the modified electrode, and for quantification of 6-TG, UA and FA in some real samples by the standard addition method.
authors: Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman, Iran. h.beitollahi@yahoo.com
authors: Hadi
authors: H
authors: Beitollahi
authors: Jahan-Bakhsh
authors: JB
authors: Raoof
authors: Rahman
authors: R
authors: Hosseinzadeh
mesh_terms: D055664:Electrochemical Techniques; D004566:Electrodes; D005492:Folic Acid / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D013866:Thioguanine / Q000032:analysis*; D014527:Uric Acid / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D014527:Uric Acid; D005492:Folic Acid; D013866:Thioguanine