title: Determination of theophylline in tea and drug formulation using a Nafion(R)/lead-ruthenium oxide pyrochlore chemically modified electrode.
abstract: Square-wave voltammetry was used for the determination of trace amounts of theophylline in tea and drug formulation at a Nafion(R)/lead-ruthenium oxide pyrochlore chemically modified electrode. This chemically modified electrode exhibits a marked enhancement of the current response compared to a bare glassy carbon electrode. The calibration graph for the determination of theophylline was linear up to 100 muM in 0.1 M, pH 3 phosphate solution with a detection limit (S/N=3) of 0.1 muM. The results of 15 successive repetitive measurement-regeneration cycles showed a relative standard deviation of 1.3% for 10 muM theophylline indicating that the electrode renewal gives a good reproducible surface. Quantitative analysis was performed by the standard addition method for the theophylline content in commercially available tea and drug.
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung 402, Taiwan, ROC.
authors.forename: J M
authors.initials: JM
authors.lastname: Zen
authors.forename: T Y
authors.initials: TY
authors.lastname: Yu
authors.forename: Y
authors.initials: Y
authors.lastname: Shih