多菌灵与Pd(Ⅱ)体系的共振瑞利散射光谱及分析应用

Resonance Rayleigh Scattering Spectra of Carbendazim Pd(Ⅱ) System and Its Analytical Application

在pH=10.0的Britton-Robinson(BR)缓冲溶液中,多菌灵与Pd(Ⅱ)反应形成1:1的六元螯合物,导致共振瑞利散射(RRS)、二级散射(SOS)和倍频散射(FDS)显著增强,并产生新的共振瑞利散射光谱,其最大RRS、SOS和FDS波长分别位于309、606和310 nm。在一定范围内,3种散射增强(ΔIRRS、ΔISOS和ΔIFDS)均与多菌灵的浓度成正比,反应具有较高的灵敏度,对于多菌灵的检出限分别为7.1×10-9 g/mL(RRS)、7.4×10-9 g/mL(SOS)和10.7×10-9 g/mL(FDS)。据此提出了测定多菌灵的光散射新方法。以灵敏度最高的RRS法为例,测定了西芹和市售农药中多菌灵的含量,结果与标准方法一致。文中还对反应机理和散射增强的原因进行了讨论。

In a Britton-Robinson（BR） buffer solution of pH=10.0,Pd（Ⅱ） and carbendazim（CBZ） can form a 1∶1 chelate complex.As a result,new spectra of resonance Rayleigh scattering（RRS）,second-order scattering（SOS）,and frequency doubling scattering（FDS） appears and their intensities are enhanced greatly.The maximum wavelengths of RRS,SOS and FDS are located at 309 nm,606 nm and 310 nm,and their intensities are proportional to the concentration of CBZ in certain ranges.The methods have a high sensitivity with the detection limit of 7.1×10-9 g/mL for RRS method,7.4×10-9 g/mL for SOS method and 1.07×10-8 g/mL for FDS method,respectively.Based on the above results,a new light scattering method for the determination of trace amounts of CBZ has been developed.The RRS method with the highest sensitivity is taken for the determination of carbendazim in celery and wettable powder.The results are consistent with those of the GB method.In addition,the reaction mechanism and the reasons of the enhancement of resonance light scattering are discussed.