Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Nov;97:915-22. doi: 10.1016/j.saa.2012.07.079. Epub 2012 Jul 31.
The luminescence arising from lanthanide cations offers several advantages over organic fluorescent molecules: sharp, distinctive emission bands allow for easy resolution between multiple lanthanide signals; long emission lifetimes (μs-ms) make them excellent candidates for time-resolved measurements; and high resistance to photo bleaching allow for long or repeated experiments. A time-resolved (gated) luminescence-based method for determination of pesticides methomyl, aldicarb and prometryne in microtiterplate format using the long-lived terbium-3-carboxycoumarin in 1:3 metal:ligand ratio has been developed. The limit of detection is 1.20×10(6), 5.19×10(5) and 2.74×10(6)ng L(-1) for methomyl, prometryne and aldicarb, respectively. The quantum yield (QY=0.08) of Tb(III)-3-carboxycoumarin was determined using 3-(2-benzothiazolyl)-7-diethylamino-coumarin (coumarin 6). Stern-volmer studies at different temperatures indicate that collisional quenching dominates for methomyl, aldicarb and prometryne. Binding constants were determined at 303, 308 and 313 K by using Lineweaver-Burk equation. A thermodynamic analysis showed that the reaction is spontaneous with negative ΔG. Effect of some relevant interferents on the detection of pesticides has been investigated.
尖锐、独特的发射带允许在多个镧系信号之间轻松分辨；长发射寿命（微秒-毫秒）使它们成为时间分辨测量的理想选择；以及对光漂白的高抗性使得长时间或重复实验成为可能。已经开发出一种基于时间分辨（门控）发光的方法，用于在微孔板格式中测定杀虫剂涕灭威、涕灭砜威和扑灭通，使用长寿命的铽-3-羧基香豆素在 1:3 的金属：配体比。涕灭威、扑灭通和涕灭砜威的检测限分别为 1.20×10(-6)、5.19×10(-5)和 2.74×10(-6)ng L(-1)。使用 3-(2-苯并噻唑基)-7-二乙氨基香豆素（香豆素 6）测定铽（III）-3-羧基香豆素的量子产率（QY=0.08）。不同温度下的 Stern-Volmer 研究表明，碰撞猝灭对涕灭威、涕灭砜威和扑灭通起主导作用。在 303、308 和 313 K 下通过 Lineweaver-Burk 方程确定结合常数。热力学分析表明，反应是自发的，ΔG 为负。还研究了一些相关干扰物对杀虫剂检测的影响。
