NOTE
Evaluation of Distribution Constants of Lanthanoid(III) Acetylacetonates between Sodium Dodecyl Sulfate Micelles and Water by Micellar Capillary Electrophoresis EXPERIMENTAL The solubilization behavior of acetylacetonate complexes of lanthanoids(III) (Nd, Sm, Tb, and Tm) in sodium dodecyl sulfate Materials micelles has been quantitatively evaluated by means of micellar Tris(acetylacetonato)neodymium(III), -samarium(III), -terbium(III), capillary electrophoresis. From analysis of the migration times of and -thulium(III) were synthesized by the procedure of Stites ( 15). Tristhe lanthanoid complexes, assuming incorporation of the cationic (acetylacetonato)iron(III) and -cobalt(III) and bis(acetylacetonato)copbis-acetylacetonates as well as the neutral tris-acetylacetonates per(II) were purchased from Dojindo Laboratory (Kumamoto, Japan). The into the anionic micelles, the distribution constant of each species metal complexes synthesized or purchased were recrystallized from ben- between the micelles and water (K mc/w ) was determined. The diszene-hexane and dried in vacuo. SDS (99% purity) was provided by tribution constants obtained were compared with those of the tris-Nakarai Tesque (Kyoto, Japan) and used without further purification. Other acetylacetonates between heptane and water (K hep/w ). The K mc/w reagents used were of analytical-reagent grade. Water was deionized and further distilled. value of the neutral complex is smaller than that of the cationic one but much larger than the K hep/w value. The K mc/w and K hep/w Methods values of the neutral complex increase with increasing atomic number of the lanthanoid, whereas the opposite tendency was MCE was performed in a fused-silica capillary 50 mm i.d., 375 mm o.d., observed for K mc/w of the cationic complex. แญง 1997 Academic Press and a length of 60 cm, filled with 5.0 1 10 03 M Na 2 B 4 O 7 buffer containing