title: Determination of caffeine using oscillating chemical reaction in a CSTR.
abstract: A new analytical method for the determination of caffeine by the sequential perturbation caused by different amounts of caffeine on the oscillating chemical system involving the manganese(II)-catalyzed reaction between potassium bromate and tyrosine in acidic medium in a CSTR was proposed. The method exposed for the first time in this work. It relies on the relationship between the changes in the oscillation amplitude of the chemical system and the concentration of caffeine. The calibration curve fits a second-order polynomial equation very well when the concentration of caffeine over the range 4.0 x 10(-6) - 1.2 x 10(-4) M (r = 0.9968). The effect of influential variables, such as the concentration of reaction components, injection point, temperature, flow rate and stirring rate were studied. Some aspects of the potential mechanism of action of caffeine on the chemical oscillating system were also discussed. A real sample was determined and the result was satisfactory.
authors.affiliation: Institute of Chemistry, Northwest Normal University, Lanzhou 730070, China. jzgao@nwnu.edu.cn
authors.forename: Jinzhang
authors.initials: J
authors.lastname: Gao
authors.forename: Jie
authors.initials: J
authors.lastname: Ren
authors.forename: Wu
authors.initials: W
authors.lastname: Yang
authors.forename: XiuHui
authors.initials: X
authors.lastname: Liu
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
mesh_terms: D002110:Caffeine / Q000032:analysis*; D002138:Calibration; D002626:Chemistry, Pharmaceutical / Q000295:instrumentation*; D004339:Drug Compounding / Q000295:instrumentation*; D007202:Indicators and Reagents; D011786:Quality Control; D013696:Temperature
chemical_list: D007202:Indicators and Reagents; D002110:Caffeine