Origin of bandbroadening on a porous polymeric HPLC packing.

摘要

Hamilton PRP-1 is a commercially available, spherical microparticulate porous poly(styrene-divinylbenzene) with a 10;The intraparticle sorption rate measurements are made under the "infinite solution volume" condition by the shallow bed technique in which about a milligram of PRP-1 is used in a bed that is about 0.3 mm in height and 3 mm diameter. The sorption rate curve, a plot of moles sorbed in the bed versus time, is successfully fit to an empirical tri-exponential equation which contains three first order sorption rate constants k;In the theoretical calculation of eluted peak shapes using the six constants, the chromatographic column is imagined to consist of three "hypothetical columns" placed in series. The shapes of the three separate peaks predicted to elute from each hypothetical column are calculated using a theoretical model. The overall theoretically predicted elution peak is obtained by mathematical convolution of the three hypothetical peaks. For comparison, the observed elution peaks are measured from an analytical HPLC column of PRP-1.;The good agreement between predicted and observed peaks demonstrates that slow intra-particle sorption is the major contribution to the excessive bandbroadening.;The nature of the slow intraparticle sorption is investigated by describing the sorption rate curve of naphthalene on PRP-1 with a monodisperse pore diffusion model (Crank) and a bidisperse pore diffusion model (Ruckenstein). The latter gives a better description of the overall sorption rate. The macropore and micropore effective diffusion coefficients are calculated from the Ruckenstein model. Micropore diffusion is diffusion into the polymer matrix.;Hamilton PRP-;The sorption isotherms of naphthalene on PRP-1 and PRP-