High-Speed Radiochemical Separations by Liquid-Liquid Chromatography Using a CSP Support. I. Performance of Quaternary Ammonium Chloride-Zipax System for the Elution of Cd(II) with HCl
The chromatographic performance of Zipax CSP support coated with tricaprylmethylammonium chloride liquid was evaluated for use in radiochemical separations by studying the elution of 109Cd(II) tracer with HCl. The concentration profiles of elutions were measured over four orders of magnitude and the resultant curves were characterized by measuring band spreading and asymmetry at 10−3 (cmax) as well as by measuring the plate height as a function of mobile phase velocity. In certain cases, the experimental and theoretical elution curves were also compared. Four Zipax particle size fractions were studied; namely, 34, 27, 19, and 14 μ average diameter. Columns were prepared by packing in a vacuum with the stationary phase frozen using the modified tap-fill method and by slurry packing. It was found that the vacuum packing procedure gave regular homogeneous packed beds with Zipax particles as small as 19 μ in diameter. Below this particle size, the slurry packing technique gave better chromatographic performance. The effect of particle size on permeability followed theory closely throughout the 34 to 14 μ particle size range. In general, the plate heights and column parameters, D and n, measured for the elution of Cd(II) at 60°C were similar in magnitude to the corresponding measurements made at room temperature for the elution of organic compounds.