钴(II)-2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚体系共振瑞利散射法测定环境 水样中十二烷基苯磺酸钠

在pH 1.8～3.0的Britton-Robinson (BR)缓冲溶液中, 钴(II)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)(HL)反应形成紫红色螯合阳离子, 此时仅能引起吸收光谱的变化, 不能导致共振瑞利散射(RRS)的增强. 当钴(II)-5-Br-PADAP螯合阳离子与阴离子表面活性剂十二烷基苯磺酸钠(SDBS)、十二烷基磺酸钠(SLS)和十二烷基硫酸钠(SDS)作用时, 仅能与SDBS进一步反应形成三元离子缔合物并引起RRS的显著增强, 而不与SDS和SLS产生类似反应. 离子缔合物的RRS峰分别位于306, 370和650 nm处, 在一定范围内RRS增强(ΔI)与SDBS浓度成正比, 当用650 nm处测量时, 其检出限为0.043 μg•mL－1, 线性范围为0.14～6.0 μg•mL－1. 文中研究了反应产物的RRS光谱特征, 适宜的反应条件及分析化学性质, 据此发展了一种在一定量SDS和SLS等阴离子表面活性剂存在下选择性测定SDBS的新方法, 方法灵敏、简便、快速，用于天然水和污水中SDBS的测定, 获得满意结果. 文中还对反应机理进行了讨论.

Resonance Rayleigh Scattering Method for the Determination of Sodium Dodecylbenzenesulfonate in Environmental Water Samples with Co(II)-2-(5-bromo-2-pyridylaro)-5-diethylaminophenol System

In pH 1.8～3.0 BR buffer medium, Co(II) was reacted with 2-(5-bromo-2-pyridylaro)-5-diethylaminophenol (5-Br-PADAP)(HL) to form a cationic chelate Co(HL)2]2＋. In this case, only the characteristics of the absorption spectra were changed, but the intensities of the resonance Rayleigh scattering (RRS) did not increase. When the cationic chelate was further reacted with some anionic surfactants such as sodium dodecylbenzenesulfonate (SDBS), sodium dodecyl sulfate (SDS) and sodium laurylsulfonate (SLS), only SDBS formed a ternary ion-association complex resulting in the great enhancement of the RRS. The RRS peaks for the ion-association complex are located at 306, 370 and 650 nm, respectively. There was a linear relationship between the RRS intensity (ΔI) and the SDBS concentration in a certain range. The detection limit was 0.043 mg•mL－1 and the linear range was 0.14～6.0 mg• mL－1 at 650 nm. In this work, the characteristics of the RRS spectra, the optimum conditions of the reaction and the properties of analytical chemistry were investigated. A new method for the selective determination of SDBS in the presence of some other anionic surfactants such as SDS and SLS has been developed, which is sensitive, simple and fast. It can be applied to the determination of SDBS in natural water and waste water samples with satisfactory results. In addition, the reaction mechanism was also discussed.