Analytical Sciences

Abstract − Analytical Sciences, 16(8), 843 (2000).

High-Performance Liquid Chromatography Using Reversed-Phase Stationary Phases Dynamically Modified with Organophosphorus Compound for the Separation and Determination of Lanthanoid Elements
Akira TSUYOSHI  and Kenichi AKIBA
Institute for Advanced Materials Processing, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan
An acidic organophosphorus compound, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPA), has been applied to reversed-phase high-performance liquid chromatography (RP-HPLC). The reversed-phase stationary phase was dynamically modified with EHPA by flowing the mobile phase of an acetone-water mixture containing the extracting reagent. The retention of lanthanoid elements was widely varied by changing the conditions of the mobile phase, i.e., the pH, the EHPA concentration and the acetone content. The selectivity of EHPA is well reflected to the chromatographic systems, and a precise separation of lanthanoid elements was achieved with sufficient resolution. The determination of Sm was examined in the presence of a large amount of Nd. A linear calibration graph was obtained for Sm at the level of 10-7 mol dm-3, in the presence of 1 x 10-4 mol dm-3 of Nd.