汞(Ⅱ)-邻菲啰啉-刚果红缔合体系的共振瑞利散射和共振非线性散射光谱及分析应用

Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Spectra of Hg(Ⅱ)-phen-CR Systems and Their Analytical Application

在pH=9.0的弱碱性环境中,Hg2+与邻菲啰啉(phen)反应形成无色螯合物[Hg(phen)3]2+,再与刚果红(CR)反应,形成三元离子缔合物Hg(phen)3CR,其摩尔比为1∶1。此时引起共振瑞利散射(RRS)、二级散射(SOS)和倍频散射(FDS)光谱显著增强,最大的散射波长分别位于578 nm(RRS法)、612 nm(SOS法)和352 nm(FDS法)。在一定条件下,散射增强(ΔI)与Hg2+浓度呈良好的线性关系,检出限分别为2.32μg/L(RRS法)、3.20μg/L(SOS法)和1.56μg/L(FDS法),考察了最佳实验条件和影响因素,表明本方法具有良好的选择性,并以RRS法为例研究了共存物质的影响。据此建立了灵敏度高、选择性好、快速准确测定Hg2+的光散射新方法,该方法用于环境水样中Hg2+的测定取得满意结果。并对RRS增强的原因和反应机理进行了讨论。

In alkaline medium of pH=9.0,Hg2＋ reacts with phenanthroline（phen） to form a colorless chelate [Hg（phen）3]2＋,which further reacts with Congo red（CR） to form 1∶ 1 ion-association complex.As a result,new peaks appear in the spectra of resonance Rayleigh scattering（RRS）,second order scattering（SOS） and frequency doubling scattering（FDS）,and their intensities are enhanced greatly.The maximum peaks of RRS,SOS and FDS are located at 378 nm,612 nm and 352 nm,respectively.The enhanced RRS,SOS and FDS intensities are directly proportional to the concentrations of Hg2＋.These methods have very high sensitivities and good selectivities,and the detection limits are 2.32 μg/L for RRS,3.20 μg/L for SOS,1.56 μg/L for FDS,respectively.In addition,the influencing factors and the effects of coexisting substances of the reaction were examined by RRS under optimum conditions.The results show that this method has a good selectivity.Therefore,a new method has been developed to determine trace amounts of Hg2＋.The reasons for RRS enhancement of the system and reaction mechanism have been investigated.