Application of a Lithium-ion Selective Metallacrown to Extraction-Spectrophotometric Determination of Lithium in Saline Water

作者：Katsuta Shoichi^*; Saito Yuki; Takahashi Suguru

来源：Analytical Sciences, 2018, 34(2): 189-193.

DOI：10.2116/analsci.34.189

• Lithium
• seawater
• extraction-spectrophotometric determination
• metallacrown

The solvent-extraction behavior of Li+ and Na+ with a Li+ selective metallacrown, [{Ru(eta(6)-3,5-dimethylanisole)(2,3-pyridinediolate)}(3)], was investigated in the presence of organic dye anions, 3',3 '',5',5 ''-tetrabromophenolphthalein ethyl ester ([TBPE](-)), 2,6-dichloroindophenolate, and picrate ([pic](-)). Each alkali metal ion was extracted as a 1:1:1 ternary complex of the metal ion, metallacrown, and anion. The Li+/Na+ extraction selectivity is anion dependent and highest with [pic](-). Therefore, we devised an extraction-spectrophotometric determination method for Li+ in saline water based on the extraction of Li+ using the metallacrown and [pic](-) for high selectivity and subsequent replacement of [pic](-) in the extracted species with [TBPE](-) for high sensitivity. When applying this to artificial seawater samples containing known concentrations of Li+, a linear relationship was observed between the absorbance at 571 nm of the organic phase and the Li+ concentration in the samples. By this method, the determination of Li+ at the sub-ppm level in natural seawater is possible.

• 出版日期2018-2