title: Flow-injection-electrochemical oxidation fluorimetry for determination of methotrexate.
abstract: A novel fluorimetric model of on-line electrochemical oxidation for the determination of methotrexate (MTX) is described in this paper. The method was based on the oxidation of MTX to a highly fluorescent product, 2,4-diaminopteridine-6-carboxylic acid, by constant potential in the electrochemical oxidation flow cell. Stopped-flow techniques were employed. Under optimal conditions, the fluorescence intensity of 2,4-diaminopteridine-6-carboxylic acid was measured at excitation and emission wavelengths of 380 and 465 nm, respectively. The calibration graph was linear over concentrations of methotrexate in the range 2.0 x 10(-7)-1.0 x 10(-5) g/mL, with a detection limit of 5.2 x 10(-8) g/mL (3sigma). The method has been successfully applied to the determination of methotrexate in human urine samples and showed a percentage recovery in the range 94.3-102.5%.
authors.affiliation: Institute of Analytical Science, School of Chemistry and Chemical Engineering, University of Southwest, Chongqing 400715, People's Republic of China.
authors.forename: Suming
authors.initials: S
authors.lastname: Chen
authors.forename: Zhujun
authors.initials: Z
authors.lastname: Zhang
authors.forename: Deyong
authors.initials: D
authors.lastname: He
authors.forename: Yufei
authors.initials: Y
authors.lastname: Hu
authors.forename: Huzhi
authors.initials: H
authors.lastname: Zheng
authors.forename: Chao
authors.initials: C
authors.lastname: He
mesh_terms: D002138:Calibration; D004563:Electrochemistry / Q000379:methods* / Q000592:standards; D017022:Flow Injection Analysis; D005470:Fluorometry / Q000379:methods* / Q000592:standards; D006801:Humans; D008727:Methotrexate / Q000652:urine*; D009862:Online Systems; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity
chemical_list: D008727:Methotrexate