丝网印刷碳电极传感器检测茶叶中痕量铅研究

Determination of Trace Lead in Tea with Screen-printed Carbon Electrodes

建立了同位镀汞法修饰的丝网印刷碳电极电化学方波溶出伏安法快速检测茶叶中的铅的方法。详细描述了建立该系统检测方法的条件优化过程，得到了一系列最佳参数：最佳的镀汞液浓度4×10^-4mol／L，沉积电位-1．1V，电位增量3mV，方波频率10Hz，方波幅度0．05V，pH值5，沉积时间280s，平衡时间30s。在优选条件下获得的方法灵敏度、线性范围和检测限分别为22．7nA/（μg／L），10—225μg／L（r=0．9986）和0．74μg／L（S／N=3）。研究了对多种重金属元素存在条件下120μg／L的铅检测的干扰情况。本试验对样品前处理方法研究发现，采用家用微波炉、聚四氟乙烯密封增压微波消化罐消化茶叶，用标准加入法对分析样品进行检测，与国标方法相比较，无显著偏差。该方法灵敏、准确、快速适合于茶叶中痕量铅的测定。

The square wave anodic stripping voltammetric （SWASV） methodology using a screen printed carbon electrode （SPCE） in situ plated in mercury （Ⅱ） was developed by the authors to determine lead in tea. A detailed description of the systematic laboratory test carried out to optimize its performance is reported. A series of optimum parameter are as follows Hg^2＋concentration： 4×10^4 mol/L, Plating potential： -1.1 V, Estep： 3 mV, Frequency： 10 Hz, Amplitude： 60 mV, pH： 5, plating time： 280 s, balance time： 30 s. Under the optimized analytical condition, the obtained sensitivity, linearity, and detection limit are 22.7 nA/（μg/L）, 10-225μg/L （r=0.9986）, and 0.74 μg/L（S/N=3）,respectively. The interference effect was thoroughly studied with various metals in the determination of 120 μg/L Pb^2＋. Tea was digested using domestic microwave oven and PTFE sealed and pressurized microwave digestion tank. The standard method of analysis was used to detect the samples and comprised with the GB method, no significant deviation was found. The method was sensitive, accurate, fast and suitable for the determination of trace lead in tea.