维脑路通分光光度法测定环境水样中痕量钼

Spectrophotometric determination of trace molybdenum in water samples with Mo(Ⅵ)-Venoruton system

采用分光光度法研究了Mo（Ⅵ）-维脑路通（VRT）络合物的形成条件及反应机理。在pH3．5HAc—NH4Ac缓冲溶液中，VRT与Mo（Ⅵ）反应生成2：1的络合物，表观形成常数为1．45×10^8，最大吸收波长位于410nm，表观摩尔吸光系数ε415=8．8×10^4L·mol^-1·cm^-1，测定Mo（Ⅵ）的线性范围为0～14μg／mL。方法用于井水、河水和湖水中痕量钼的测定，相对标准偏差分别为1．3％，2．6％和1．8％，加标回收率分别为97．5％，100．3％和101．6％。

This work is aimed to investigate the conditions for the formation of Mo（Ⅵ）-Venoruton （VRT） complex and the reaction mechanism with spectrophotometric method. In the buffer solution of HAc-NH4Ac（pH 3.5） ,it is found that VRT and Mo（Ⅵ） form a stable binary complex （2 ： 1） ,whose apparent formation constant is 1.45 × 10^8 and maximum absorbent wavelength is 410 nm. The calibration curve was linear in the range of 0--14μg/mL for Mo（Ⅵ）, with apparent molar absorptivity of 8.8 × 10^4 L · mol^-1 · cm^-1. The method has been applied to the determination of trace molybdenum in samples from well water, river water, and lake water. The relative standard deviations were 1. 3%, 2. 6%,1.8% and the recoveries were 97. 5%,100.3%,101.6%, respectively.