Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt.
J Fluoresc. 2012 Mar;22(2):659-76. doi: 10.1007/s10895-011-1002-4. Epub 2011 Nov 3.
This work describes the application of time resolved fluorescence in microtiterplates and electrochemical methods on glassy carbon electrode for investigating the interactions of europium-3-carboxycoumarin with pesticides aldicarb, methomyl and prometryne. Stern-volmer studies at different temperatures indicate that static quenching dominates for methomyl, aldicarb and prometryne. By using Lineweaver-Burk equation binding constants were determined at 303 K, 308 K and 313 K. A thermodynamic analysis showed that the reaction is spontaneous with ΔG being negative. The enthalpy ΔH and the entropy ΔS of reactions were all determined. A time-resolved (gated) luminescence-based method for determination of pesticides in microtiterplate format using the long-lived europium-3-carboxycoumarin has been developed. The limit of detection is 4.80, 5.06 and 8.01 μmol L(-1) for methomyl, prometryne and aldicarb, respectively. This is the lowest limit of detection achieved so far for luminescent lanthanide-based probes for pesticides. The interaction of the probe with the pesticides has been investigated using cyclic voltammetry (CV), differential pulse polarography (DPP), square wave voltammetry (SWV) and linear sweep voltammetry (LSV) on a glassy carbon electrode in I = 0.1 mol L(-1) p-toluenesulfonate at 25 °C. The diffusion coefficients of the reduced species are calculated. The main properties of the electrode reaction occurring in a finite diffusion space are the quasireversible maximum and the splitting of the net SWV peak for Eu(III) ions in the ternary complex formed . It was observed that the increase of the cathodic peak currents using LSV is linear with the increase of pesticides concentration in the range 5 × 10(-7) to 1 × 10(-5) mol L(-1). The detection limit (DL) were about 1.01, 2.23 and 1.89 μmol L(-1) for aldicarb, methomyl and prometryne, respectively. In order to assess the analytical applicability of the method, the influence of various potentially interfering species was examined. Influence of interfering species on the recovery of 10 μmol L(-1) pesticides has been investigated.
这项工作描述了时间分辨荧光在微孔板和电化学方法在玻碳电极上的应用，用于研究铕-3-羧酸香豆素与农药涕灭威、灭多威和二甲戊乐灵的相互作用。在不同温度下的 Stern-Volmer 研究表明，静态猝灭对灭多威、涕灭威和二甲戊乐灵起主导作用。通过使用 Lineweaver-Burk 方程，在 303 K、308 K 和 313 K 下确定了结合常数。热力学分析表明，反应是自发的，ΔG 为负值。反应的焓ΔH 和熵ΔS 均已确定。已经开发出一种基于时间分辨（门控）荧光的微板格式测定农药的方法，使用长寿命的铕-3-羧酸香豆素。涕灭威、二甲戊乐灵和涕灭威的检测限分别为 4.80、5.06 和 8.01 μmol L(-1)。这是迄今为止基于镧系元素探针测定农药的最低检测限。使用循环伏安法（CV）、差分脉冲极谱法（DPP）、方波伏安法（SWV）和线性扫描伏安法（LSV）在 25°C 下，在 I = 0.1 mol L(-1) 对甲苯磺酸盐中，在玻碳电极上研究了探针与农药的相互作用。计算了还原物种的扩散系数。在有限扩散空间中发生的电极反应的主要性质是形成三元配合物后 Eu(III) 离子的准可逆最大和净 SWV 峰的分裂。观察到使用 LSV 增加的阴极峰电流与三元配合物中农药浓度在 5×10(-7) 至 1×10(-5) mol L(-1)范围内的增加呈线性关系。检测限（DL）分别约为 1.01、2.23 和 1.89 μmol L(-1) 用于涕灭威、灭多威和二甲戊乐灵。为了评估该方法的分析适用性，研究了各种潜在干扰物质的影响。考察了干扰物质对 10 μmol L(-1) 农药回收率的影响。
