维生素B12与12-钨磷酸相互作用的双波长共振瑞利散射光谱及其分析应用

建立了一种双波长共振瑞利散射光谱测定维生素B12的新方法. 在pH=1.0的HCl介质中, 维生素B12(VB12)与12-钨磷酸(TP)形成摩尔比为3:1的离子缔合物, 导致双波长共振瑞利散射(DWO-RRS)、 二级散射(SOS)和倍频散射(FDS)光谱显著增强, 其最大散射波长分别位于330和370 nm(RRS), 608 nm(SOS)和386 nm(FDS). 在一定范围内, 3种散射增强(ΔIRRS, ΔISOS和ΔIFDS)均与VB12的浓度成线性关系. 该方法具有较高的灵敏度, RRS, SOS和FDS法对VB12的检出限(3σ)在2.0~7.6 ng/mL之间. 研究了反应条件和共存物质的影响, 结果表明, 该方法具有良好的选择性. 据此, 提出了简便、 快速、 准确且高灵敏测定痕量VB12的光散射新方法, 适用于片剂和尿样中VB12的测定. 还对反应机理和散射光谱增强的原因进行了讨论.

Dual-wavelength Overlapping Resonance Rayleigh Scattering Spectra of the Interactions of Vitamin B12 with 12-Tungstophosphoric Acid and Their Analytical Applications

A new dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed to detect vitamin B12(VB12) with 12-tungstophosphoric acid(TP). In a HCl medium(pH=1.0), VB12 could react with TP to form a 3: 1 ion-association complex. As a result, the new spectra of DWO-RRS, second order scattering(SOS) and frequence doubling scattering(FDS) appeared and their intensities were enhanced greatly. Their maximum wavelengths were located at 330 nm(RRS), 370 nm(RRS), 608 nm(SOS) and 386 nm(FDS), respectively. The three kinds of scattering intensities(ΔIRRS, ΔISOS and ΔIFDS) were proportional to the concentration of VB12 in certain ranges. The methods had high sensitivity with the detection limit of 2.0-7.6 ng/mL. The optimal conditions and the effects of coexistent substances of RRS method were investigated. So, a simple, rapid and new method had been proposed to determine trace VB12. It had been applied to the determination of VB12 in urine samples and vitamin B12 tablets with satisfactory results. In addition, the reasons for RRS enhancement and composition of ion-association complex were discussed.