以甲基丙烯酸甲酯(MMA)预聚物作为石墨粉的粘合剂,制备了一种电化学性能优越的聚合物石墨复合电极(PMMA-CPE),该电极能有效改善传统碳糊电极(CPE)的机械强度,提高检测重现性和电极表面电子传递速率。采用循环伏安法、计时库仑法研究了壬基酚(nP)在PMMA-CPE上的电化学行为,并考察了支持电解质、扫速、pH值等对测定的影响。实验结果表明nP在PMMA-CPE上是受吸附控制的完全不可逆的2电子2质子的电极过程。在最优条件下,采用安培检测法测得nP的氧化峰电流与其浓度在5.0×10-8~7.0×10-7mol/L和9.0×10-7~3.0×10-5mol/L范围内呈良好的线性关系,检出限(S/N=3)为6.62×10-9mol/L。该方法简便、快速,用于实际水样及土壤样品中痕量nP的分析检测,加标回收率为94%~103%。
In this paper,viscous methylmethacrylate(MMA) was prepolymerized as an hand-mixed adhesive for the fabrication of a composite graphite/poly(methylmethacrylate) electrode with high electrochemical performance.Compared with the traditional carbon paste electrode,the electrode fabricated behaves better in mechanical property,stability and reproducibility.The behavior of nonyl phenol(nP)at composite graphite/PMMA electrode was studied by SEM and impedance spectroscopy.Factors influencing the detection processes of nP such as supporting electrolyte,pH value and scan rate were also investigated and optimized.The results indicated that an adsorption-controlled process with 2 electrons and 2 protons transfer occurred at the proposed electrode and the oxidation process for nP was completely irreversible.Under the optimized conditions,a sensitive method of amoperometric measurement was established for the detection of nP at the graphite/PMMA composite electrode.The calibration curve was linear over the nP concentrations in the ranges of 5.0×10-8-7.0×10-7 mol/L(r=0.998)and 9.0 ×10-7-3.0×10-5 mol/L(r=0.996) with a detection limit(S/N=3) of 6.62×10-9mol/L.The proposed method was simple and rapid,and was applied in the determination of nP in real water and soil samples with good recoveries of 94%-103%.