title: Quantitation of caffeine by capillary zone electrophoresis with end-column amperometric detection at a carbon microdisk array electrode.
abstract: Capillary zone electrophoresis is employed for the determination of caffeine using end-column amperometric detection with a carbon fiber microdisk array electrode at a constant potential of 1.45 V versus a saturated calomel electrode. The optimum conditions of separation and detection are 0.1 52mM NaH2PO4-0.648mM Na2HPO4 for the buffer solution, 20 kV for the separation voltage, 5 kV for the injection voltage, and 10s for the injection time. The limit of detection is 2.9 x 10(-4)mM or 1.2 fmol (signal-to-noise ratio = 2). The relative standard deviation is 0.68% for the migration time and 2.3% for the electrophoretic peak current. The method is applied to determining caffeine in human serum and a cola drink.
authors.affiliation: Laboratory of Analytical Science, School of Chemistry, Shandong University, China.
authors.forename: W
authors.initials: W
authors.lastname: Jin
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: Q
authors.initials: Q
authors.lastname: Dong
authors.forename: X
authors.initials: X
authors.lastname: Ye
mesh_terms: D001628:Beverages / Q000032:analysis; D002110:Caffeine / Q000032:analysis* / Q000097:blood; D002244:Carbon; D004566:Electrodes; D019075:Electrophoresis, Capillary / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002110:Caffeine; D002244:Carbon