高等学校化学学报 ›› 1988, Vol. 9 ›› Issue (9): 897.

• 论文 • 上一篇    下一篇

双显色剂高灵敏协同显色反应的研究——钼-溴邻苯三酚红-乙基紫体系

沈含熙, 刘跃龙   

  1. 南开大学化学系
  • 收稿日期:1987-04-28 出版日期:1988-09-24 发布日期:1988-09-24
  • 通讯作者: 沈含熙

High Sensitive Synergistic Chromophoric Reactions by Double Chromogenic Reagents——Molybdenum-Bromopyrogallol Red-Ethyl Violet System

Shen Hanxi, Liu Yuelong   

  1. Department of Chemistry, Nankei University, Tianjin
  • Received:1987-04-28 Online:1988-09-24 Published:1988-09-24

摘要: 本文研究了在聚乙烯醇存在下,钼(Ⅵ)与溴邻苯三酚红和碱性染料-乙基紫产生的协同显色反应。探讨了利用协同显色反应进行分光光度测定痕量钼的可能性。在乙酸介质中,钼(Ⅵ)与溴邻苯三酚红和乙基紫形成[EV]3[MoO2(BPR)]离子缔合型配合物,其吸收峰位于535nm,相应试剂(BPR+EV)的吸收峰则位于640nm。摩尔吸光系数e536=1.70×105L·mol-1·cm-1。双峰双波长法可使灵敏度倍增。Δε535~640=3.20×105L·mol-1。钼含量为0~0.16μg/mL时,吸光度遵守比尔定律。桑德尔灵敏度(S)为0.00057μg/cm2。反应具有较高的选择性,除锗、钛、钨、钒有较严重干扰以外,其它常见金属离子不干扰钼的显色。根据配合物的组成,推测了它的可能结构。

关键词: 钼的测定, 溴邻苯三酚红, 乙基紫, 协同显色反应, 双波长分光光度法

Abstract: In the presence of polyvinylalcohol molybdenum ions(Ⅵ) can form a colour product with both bromopyrogallol red and ethyl violet. Owing to the increasing of the effective absorption section area of chromogenic molecules, the reaction sensitivity is enhanced remarkably. This paper describes the experimental conditions of above mentioned synergistic chromophoric reaction, composition of complex formed and related reaction mechanism, and a procedure for the spectroph-otometric determination of trace molybdenum. In an acetic acid medium molybdenum ions form an ion-associate complex with a definite composition of Mo:BPR:EV = 1:1:2, with both Bromopyrogallol red and ethyl violet, and its corresponding molecular form is [EV]2 [MoO2(BPR)]. The maximum absorption of molybdenum complex was located at 535 nm, in the meantime the reagents (BPR + EV) exhibited maximum absorption at 640 nm. The apparent molar absorptivity of the complex is ε535= 1.70×105L·mol-1. cm-1. If the dual peak-dual wavelength method is used for the determination, the sensitivity of the method will be doubled., Δε535~640= 3.20×105 L·mol-1·cm-1. Beer's law is obeyed for the molybdenum concentration 0~0.16μg/mL. The Sandell's sensitivity is 0.00057μg/cm2. Reaction is highly selective. The common metal ions do not interfere with molybdenum reaction except germanium, titanium and tungsten ions

Key words: Molybdenum determination, Bromopyrogallol red, Ethyl violet, Synergistic colour reaction, Dual-wavelength spectrophotometry

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