Bi(Ⅲ)-茜素红-十六烷基三甲基溴化铵体系共振散射光谱法测定环境水样中痕量铋

Determination of Trace Bi(Ⅲ) in Environmental Water Samples with Alizarin Red-Bi(Ⅲ)-CTMAB System by Resonance Light Scattering Spectroscopy

在pH=4.1的HCl溶液中,Bi(Ⅲ)与茜素红和十六烷基三甲基溴化铵(CTMAB)缔合形成粒径较大的疏水性三元离子缔合物(结合比为n(Bi(Ⅲ))∶n(AR)∶n(CTMAB)=1∶3∶3),该反应导致共振光散射显著增强,最大散射峰位于364nm。研究了反应介质、pH值、共振探针浓度等对散射体系的影响,考察了该散射反应的稳定性及共存物质的影响,并对该三元离子缔合物的反应机理进行了探讨。在2.5mL1.0×10-4mol/L茜素红和2.0mL1.0×10-4mol/LCTMAB最优试验条件下,Bi(Ⅲ)质量浓度与共振光散射强度ΔI364nm在0～0.384mg/L范围内呈良好线性关系,检测限为5.898×10-8g/L,对含量为0.18mg/LBi(Ⅲ)溶液进行11次平行测定,其相对标准偏差为2.2%。将该方法用于环境水样中痕量铋(质量浓度为0.552～0.831μg/L)的测定,加标回收率为99.5%～100.2%,测定偏差小于2.7%。基于Bi(Ⅲ)-AR-CTMAB三元离子缔合物的共振光散射光谱,建立了以茜素红染料为光谱探针的痕量Bi(Ⅲ)共振光散射检测新方法。

In hydrochloric acid solution with pH=4.1,Bi（Ⅲ） can react with alizarin red（AR） and cetyltrimethylammonium bromide（CTMAB） to form ternary ion-association complexe particles（the combination proportion was defined as n（Bi（Ⅲ））：n（AR） ：n（CTMAB）=1：3：3）.In this case,the resonance light scattering（RLS） intensities are enhanced greatly.The maximum RLS wavelength locates at 364 nm.The optimal conditions of the reaction,influence factors and the effect of coexisting substances were investigated.In addition,the reaction mechanism of the ternary ion-association complex was discussed.Under the optimal experimental conditions of 2.5 mL 1.0×10^-4 mol/L alizarim red and 2.0 mL 1.0×10^-4 mol/L CTMAB,the resonance scattering intensity（ΔI364 nm） was linearly related to the concentration of Bi（Ⅲ） in the range of 0～0.384 mg/L with a detection limit of 5.898×10-8 g/L.The method can be applied to the determination of Bi（Ⅲ） in water samples.The result was satisfactory and the recoveries were 99.5%～100.2% at the concentrations ranging from 0.552 to 0.831 μg/L,and the relative standard deviation was less than 2.7%.A sensitive,simple and new resonance light scattering method for determination of trace amount of Bi（Ⅲ） in environment was set up using the alizarin red as a spectrum probe.