メチルキシレノールブルーによるジルコニウムの吸光光度定量

概要

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Zirconium formed a red-violet complex with Methylxylenol Blue (MXB) in weakly sulfuric acid solution. This complex showed an absorption maximum at 575 nm, and the absorbance was constant over the acidity range from 0.180.28N (sulfuric acid). The calibration curve was linear for 560 μg of zirconium in 25 ml solution. The molar absorptivity was about 14, 000. The analytical procedure was as follows. A sample solution containing 560 μg zirconium was mixed with suitable amounts of 1N sulfuric acid and 1.0 ml of 0.1% MXB, and made up to 25 ml with water (the final acidity 0.180.28N). It was then heated in a water bath of 55 ± 2°C for 3 minutes. After 5 minutes, the absorbance of the colored solution was measured at 570 nm against the reagent blank. Many ions did not interfere, but bismuth, hafnium, thorium, iron (III) and fluoride interfered even when their amounts were one fold of zirconium. The permissible amounts of iron (III) was increased by addition of thioglycollic acid.