差示紫外光度法测定氯锇酸铵的纯度

Determination of Purity of Ammonium Chloroosmate with differential Ultraviolet Spectrophotometry

研究了(NH_4)_2OsCl_6及共存离子的紫外吸收光谱。在369nm波长处(NH_4)_2OsCl_6有一个稳定的吸收峰,其摩尔吸光系数为7.6×10~3,在很宽的浓度范围内服从比尔定律。将试样简单地溶于0.5mol/L HCl溶液中即可进行差示光度测定。试样含量为99％时,方法的变异系数小于0.09％。本文确证了影响光谱纯氯锇铵纯度的主要杂质为NH_4Cl,并给出了氯锇酸铵标准的标定方法。

The ultraviolet absorption spectra of (NH_4)_2Os Cl_6 and coexisting metal ions have been investigated. There is an absorption maximum at the wavelength 369nm for (NH_4)_2OsCl_6 with the molar absorptivity 7.6×10 L.mol^(-1). cm^(-1). Lambert-Beer's law is obeyed. A differential spectrophotometric method has been developed. The absorbance of (NH_4)_2Os Cl_6can simply be measured after dissolving a sample in 0.5 mol/L HCI solution. The RSD was less than 0.09% when about 99% of (NH_4)_2OsCl_6 was determined . It has been confirmed thatthe major impurity in spectroscopically pure ammonium chorosmate is NH4_Cl. A method for standardization of ammonium chlorosmate as a standard has also been given.