The sulfanilic acid functionalized graphene sheets (AS-GS ) and methanol solution of 0.1%nafion are used to fabricate a new type of composite film modified electrode . T he modified electrode is characterized by scanning electron microscope (SEM ) . The electrochemical behaviors and kinetic properties of caffeine on the modified electrode are investigated by cyclic voltammetry (CV ) and the differential pulse voltammetry(DPV) . The modified electrode displays excellent electrochemical catalytic activities toward the oxidation of caffeine under the optimum condition . The peak current is linearly dependent on the CAF concentrations in the range of 1~500 μmol·L -1 with the detection limit (S/N=3) of 5.31 × 10-7 mol·L -1 . In addition , the composition film of AS-GS/Nafion modified electrode show s high sensitivity ,favorable stability and reproducibility .Moreover ,AS-GS/Nafion modified electrode has been applied to the quick determination of CAF in the cola and functional beverage .%以对氨基苯磺酸功能化石墨烯（AS-GS）和0.1％ Nafion的甲醇溶液制备了一种新型的复合膜修饰电极．采用扫描电镜（SEM）对修饰电极进行了表征，并利用循环伏安法（CV）和微分脉冲伏安法（DPV）研究了咖啡因（CAF）在修饰电极上的电化学行为．在最优条件下，修饰电极对咖啡因的氧化有良好的电催化活性，氧化峰电流与咖啡因浓度在1～500μmol·L -1范围内呈良好的线性关系，检测限为5.31×10-7 mol·L -1（S/N＝3）．此外， AS-GS/Nafion复合膜修饰电极具有较高的灵敏性，较好的稳定性和重现性，可用于可乐和功能性饮料中咖啡因含量的快速检测．
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