エチルバイオレットと銅(I)クロロ錯イオンのイオン会合抽出による鉄鋼及びアルミニウム合金中の銅の吸光光度定量

Cu(I)クロロ錯陰イオンとエチルバイオレットとのイオン会合体の溶媒抽出-吸光光度法による鉄鋼及びアルミニウム合金中のCuの定量方法を確立した.試料を希硫酸又は王水で溶解し,ほぼ蒸発乾固する.王水を使用した場合,更に希硫酸を加え,ほぼ蒸発乾固する.その後定容とし,試料溶液として用いる.この一定量を抽出管に取り,アスコルビン酸でCUを還元し,塩化物イオンの存在下,酢酸塩緩衝液でpH4.1付近に調整後,エチルバイオレット溶液を加え,生成したイオン会合体をトルエン相に抽出する.このトルエン相の612nmでの吸光度を測定し, Cuの定量を行う.本法は高感度(モル吸光係数約10(5)),高選択的,特にモル比でFeがCuの11000倍量共存しても妨害とはならず試料中の0.011%程度のCuの定量も可能であった.

Trace amounts of Cu in steel, stainless steel and aluminium alloys were spectrophotometrically determined after solvent extraction of an ion associate formed between dichlorocopper(I) ion (CuCl(2)(-)) and Ethyl Violet. The procedure is as follows. Dissolve the sample by heating with dilute sulfuric acid or aqua regia. Then, evaporate the resulting solution nearly to dryness. If aqua regia is used for dissolution of the sample, add dilute sulfuric acid to the resulting solution and evaporate nearly to dryness. Dilute the residue to a fixed volume with water. Pipette an adequate volume of the sample solution into a stoppered test tube. Add ascorbic acid and potassium chloride solutions, and adjust the pH of the solution to about 4.1 with acetate buffer. Add Ethyl Violet solution and extract the ion associate formed between dichlorocopper (I) ion and Ethyl Violet to 5 ml of toluene. Measure the absorbance of the organic phase at 612nm. The proposed method is very sensitive (molar absorptivity: 10(5) l mol(-1) cm(-1)) and the interference of coexisting ions is negligible. Copper above 0.011% in the sample can be determined by this method.