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.