汞-邻菲啰啉-刚果红缔合体系光度法测定痕量汞

Photometric Determination of Trace Amount of Mercury by the Ion Association System of Hg(Ⅱ)-Phen Anthroline and Congo Red

在含有汞(Ⅱ)试液中,先后加入乙酸-乙酸钠缓冲溶液(pH 5.7)、1.0×10-3mol.L-1邻菲啰啉溶液0.8 mL、4.0×10-4mol.L-1刚果红溶液1.2 mL及10 g.L-1阿拉伯树胶(GA)溶液0.8 mL使反应生成汞与邻菲啰啉和刚果红的络合物。在此缔合体系中,GA对显色反应兼有增敏和增稳作用。汞(Ⅱ)质量浓度在1.0 mg.L-1范围内与其吸光度呈线性关系。反应体系的吸收峰位于540 nm波长处,在此波长条件下测定其表观摩尔吸光系数为8.49×104L.mol-1.cm-1。此方法已应用于测定河水中汞量,求得相对标准偏差(n=5)小于2.0%,平均回收率为100.4%。

Mercury（Ⅱ） was reacted with 0.8 mL of 1.0×10-3mol·L-1 o-phenanthroline solution and 1.2 mL of 4.0×10-4mol·L-1 congo red in an HOAc-NaOAc buffer solution of pH 5.7 with addition of 0.8 mL of 10 g·L-1 gum arabic solution both as sensitizer and stabilizer,to form an ion-association complex.Linearity between values of absorbance and mass concentration of Hg（Ⅱ） was found in the range within 1.0 mg·L-1.Apparent molar absorptivity of the association complex found was 8.49×104L·mol-1·cm-1 at the wavelength of its absorption maximum,540 nm.The proposed method was applied to the determination of mercury in samples of river water,giving RSD′s（n=5） less than 2.0% and average recovery of 100.4%.