对羟基苯甲酸酯分子印迹电化学传感器的研制

利用分子印迹技术,以对羟基苯甲酸乙酯为模板分子,甲基丙烯酸为单体,在玻碳电极表面原位聚合分子印迹聚合物敏感膜.采用方波伏安法对对羟基苯甲酸乙酯在该印迹电极上的电化学行为进行了研究,当响应时间为15 min时,0.95 V(vs SCE)处的峰电流与对羟基苯甲酸乙酯的浓度在2.0×10-6 ～2.0×10-4 mol/L范围内呈线性关系,检出限(S/N=3)为1.0 μmol/L,而相同条件下,对羟基苯甲酸乙酯在控制电极上的响应非常小并对浓度变化不灵敏;同时在印迹电极上氧化峰电位较在裸电极上发生了微弱正移.同一支印迹电极对对羟基苯甲酸乙酯响应值的RSD为4.3%(n=10).该印迹电极对尼泊金酯类具有良好的选择性,对对羟基苯甲酸甲酯、丙酯以及丁酯的选择性系数分别为1.89、1.70和2.01;对结构相似的苯酚、对羟基苯甲酸、对氨基苯甲酸等响应不灵敏,对结构差异较大的如维生素C等几乎无响应.用该分子印迹电极对实际样品进行分析,加标回收率大于90%.

Preparation of Electrochemical Sensor for Parabens Based on Molecularly Imprinted Polymers

A molecularly imprinted polymers(MIPs) was synthesized by using ethyl paraben(EP) as template and methacrylic acid as functional monomer,and a molecularly imprinted electrode was constructed on the surface of a glassy carbon electrode for determination of parabens,such as EP,methyl paraben(MP),butyl paraben(BP) and propyl paraben(PP).Electrochemical oxidation behaviors of EP on the imprinted electrode were investigated by square wave voltammetric method.When using the incubation time of 15 min,the peak currents at oxidation potential of 0.95 V(vs SCE) were proportional to the concentration of EP in the range of 2.0×10-6 to 2.0×10-4 mol/L with a detection limit of 1.0 μmol/L(S/N=3).The RSD(n=10) of the imprinted electrode for peak current was 4.3%(n=10).Under the same conditions,the extremely small responses of the control electrode were observed and independent of the analyte concentration.The oxidation potential of EP recorded with imprinted electrode was a slight positive shift comparing with that of the bare electrode.The imprinted electrode also displayed good specific binding MP,PP and BP,and their selective coefficients of imprinted electrode were 1.89,1.70 and 2.01,respectively.Structural analogs,such as phenol,p-hydroxybenzoic acid and p-aminobenzoic acid,only small responses electrode were observed.Moreover,structural unanalog vitamin C had almost no response.The imprinted electrode was used for analysis of parabens in actual samples with the spiked recoveries more than 90%.The molecularly imprinted polymer electrode showed good sensitivity and selectivity,and was simple to construct and operate.