Abstract
The spectrophotometric determination of $Lu^{3+},\;Eu^{3+}$ and some other rare earths have been investigated using Methyl Thymol Blue(MTB) as spectrophotometric reagent. Rare earth elements form a stable complex with MTB abount pH 6.5 and the ratio of its complex is 1 to 1. MTB has a absorption maxima at 440nm and rare earth MTB complex has absorption maxima 610nm at pH 6.5, respectively. The absorbance of the rare earth MTB complex is stable in 7 hours after color developing and obey the Beer law in the range of $0{\sim}110{\mu}g/50ml$. The ligand such as phosphate, citrate and EDTA decrease the absorbance of its complex considerably, and this method has a poor selectivity of each rare earth element and the molar absorptivity is $1.2{\sim}2.0{\times}10^4mol^{-1}{\cdot}l{\cdot}cm^{-1}$. In methyl alcohol, ethyl alcohol and acetone medium we did not find out any absorption change of the rare earth MTB complex.
Methyl Thymol Blue(MTB) 발색시약을 사용하여 $Lu^{3+},\;Eu^{3+},\;Sm^{3+}$ 및 $Pr^{3+}$ 원소의 흡수분광광도법에 의한 정량법을 확립하였다. ligand와 금속의 몰비는 1:1이었으며 Hexamethylenetetramine 완충용액으로 pH 6.5로 만들었을 때 MTB의 최대흡수파장은 440 nm이며 희토류-MTB 착물의 최대흡수파장은 610 nm로 나타났고 용액의 흡광도는 발색 후 7시간 정도까지 일정한 흡광도를 나타내며 $0{\sim}110{\mu}g/50ml$의 범위에서 Beer의 법칙에 따른다. phosphate, EDTA, citrate같은 리간드이온들은 희토류 -MTB의 흡광도에 크게 영향을 주며 각각의 희토류 원소분석의 선택성은 없다. 메틸알코올, 에틸알코올 및 아세톤 용매에서도 희토류-MTB 용액의 흡광도는 변하지 않았다. 몰흡광계수는 $1.2{\sim}2.0{\times}10^4mol^{-1}{\cdot}l{\cdot}cm^{-1}$이다.