分光光度研究稀土-偶氮氯膦Ⅲ-溴化十六烷基兰甲胺三元络合物

分光光度研究稀土-偶氮氯膦Ⅲ-溴化十六烷基兰甲胺三元络合物 SPECTROPHOTOMETRIC STUDY OF THE TERNARY COMPLEXES OF RARE EARTHS-CHLOROPHOSPHONAZO Ⅲ-CETYL TRIMETHYL AMMONIUM BROMIDE 罗庆尧 Luo Qingyao Shi Guangzhao Zeng Yune first-author 史广昭 曾云鹗 <正> 偶氮膦Ⅲ在pH1-2的酸性介质中与稀土元素形成兰绿色的络合物,广泛地应用于铸铁、低合金钢中稀土总量的光度测评[1-4]。但是,一些重金属如铬、镍、铜、钻、锰、钨等的干扰仍较严重,当用于复杂试样中稀土测定时,仍需采取分离步骤。我们在探讨稀土、偶氮氯膦Ⅲ与各种阳离子表面活性剂反应行为的基础上,研究了稀土—偶氮氯膦Ⅲ—溴化十六烷基三甲胺三络合物体系,反应适宜酸度是1.5～2.0N HCl,络合物最大吸收在721～723nm。显色反应体系具有更高的灵敏度和选择性。可不经分离直接光度测定合金钢中微最稀土元素总量。 Chlorophosphonazo Ⅲ（CP Ⅲ）reacts with rare earths in the presence of cetyl trimetbyl ammonium bromide （CTAB） to form blue-violet ternary complexes. Their absorption maximum are at 722 nm. To the test solution containing 1 ml of 1.227×10 -4 M rare earth. 8 ml of 6N hyarchtoric acid solution, 1.5ml of 0.2% CTAB. 2.5ml of enthaaol and 1ml of 0.2% CP Ⅲ are added in proper order. Then the solution is diluted to 25ml with water. The absorbance at 722 am is measured against the reagent blank. The absorbance was stable for at least 2 hours. The ternary complexes of rare earths not only have the same absorption maximum but also the apparent molar absorpivity is very much the same. These complexes are slightly insolule in water but they are soluble in ethanol. As the result of the mole ratio method and the continuous variation method the compsition of the complex is estimated to be 1:2（La: Cp Ⅲ）and 1:3 （La: CTAB） 1981-03-01 2021-04-01 3