铁(Ⅲ)-硫氰酸根-乙基罗丹明B缔合体系微乳液分光光度法测定铝合金中铁
Micro-emulsion Spectrophotometric Determination of Iron in Aluminum Alloy by the Associated System of Fe(Ⅲ)-Thiocyanate-Ethyl Rhodamine B
-
摘要: 提出了微乳液分光光度法测定铝合金中铁含量的方法。在比色管中,先后加入0.5 mol·L-1硫酸溶液3.00 mL、铁(Ⅲ)标准溶液,2 mol·L-1硫氰酸钾溶液3.00 mL、5 g·L-1阿拉伯树胶溶液0.8 mL、微乳液0.70 mL及1×10-3mol·L-1乙基罗丹明B溶液3.00 mL使反应生成铁与硫氰酸盐的络阴离子和乙基罗丹明B的缔合物。微乳液和阿拉伯树胶对此显色体系具有显著的增溶作用。铁(Ⅲ)的质量浓度在0.026~0.36 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波长620 nm处,在此波长条件下测定其表观摩尔吸光率为1.08×105L·mol-1·cm-1。方法用于测定铝合金试样中铁量,测定值的相对标准偏差(n=5)小于2%。Abstract: A micro-emulsion spectrophotometric method for determination of iron in aluminum alloy was proposed. Fe (Ⅲ) was reacted with 3.00 mL of 2 mol·L-1 KSCN solution and 3.00 mL of 1.0×10-3mol·L-1 ethyl rhodamine B in 0.5 mol·L-1 H2SO4 solution in the presence of 0.8 mL of 5 g·L-1 gum arabic and 0.70 mL of micro-emulsion solution. An association complex was formed between the anionic complex of ［Fe(CN)6］3- and the cation of ethyl rhodamine B (ERB+), which was solubilized by solutions of gum arabic and micro-emulsion. Linear relationship between values of absorbance and mass concentration of Fe(Ⅲ) was found in the range of 0.026-0.36 mg·L-1. Apparent molar absorptivity of the associated system found was 1.08×105L·mol-1·cm-1 at the wavelength of its absorption maximum 620 nm. The proposed method was applied to the determination of Fe in samples of aluminum alloy, giving values of RSD′s (n=5) less than 2%.
下载: