Analytical Sciences

Abstract − Analytical Sciences, 24(1), 133 (2008).

Magnetophoretic Evaluation of Interfacial Adsorption of Dysprosium(III) on a Single Microdroplet
Masayori SUWA and Hitoshi WATARAI
Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
Magnetophoretic velocimetry is a novel technique to measure the magnetic susceptibility of a single microparticle. This techinique could be applied to study the interfacial adsorption equilibria of a paramagnetic dysprosium(III) ion with capric, lauric or stearic acid for a single 2-fluorotoluene microdroplet. The observed magnetic susceptibility of the micro-organic droplets was reciprocally proportional to its radius in each case. From the proportional constant, the interfacial concentration of Dy(III) was determined. Furthermore, the dependences of the interfacial concentration on the initial Dy(III) concentration and pH were examined in order to analyze the adsorption equilibrium. Finally, the saturated interfacial concentration and the interfacial adsorption constant at the infinite dilution of Dy(III)-laurate complex were evaluated as 4.8 × 10-10 mol cm-2 and 3.4 × 10-2 dm, respectively.