A BRIEF STUDY OF THE SUPERCRITICAL-FLUID CHROMATOGRAPHIC BEHAVIOR OF LANTHANIDE BETA-DIKETONATES

The chromatographic behaviors of lanthanide chelates of acetylacetone (ACAC), trifluoroacetylacetone (TFA), thenoyltrifluoroacetone (TTA), d ipivaloylmethane (THD), 7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octaned ione (FOD), and the thenoyltrifluoroacetone-pyridine (TTA Py) adduct w ere investigated using packed column supercritical fluid chromatograph y. Mobile phases consisting of neat and alcohol modified CO2 were used with a phenyl packed stationary phase. Lanthanide complexes of ACAC, THD, and FOD were shown to have better chromatographic performance com pared to the corresponding chelates with TFA, TTA, and TTA Py. In part icular, TTA complexes such as Eu(TTA)(3) showed characteristic thermal decomposition in the mobile phase at elevated temperature. In additio n, retention behavior was found to be a temperature dependent function of volatility and solubility for all chelates studied.