A New Method To Determine Dispersive Surface Energy Site Distributions by Inverse Gas Chromatography

A computational model to predict the relative energy site contributions of a heterogeneous material from data collected by finite dilution inverse gas chromatography (FD-IGC) is presented in this work. The methodology employed a multisolvent system site filling model utilizing Boltzmann statistics, expanding on previous efforts to calculate experienced energies at varying coverage, yielding a retention volume distribution allowing calculation of a surface free energy distribution. Surface free energy distributions were experimentally measured for racemic ibuprofen and beta-mannitol powders, the energies of each were found in the ranges 43-52 and 40-55 mJ/m(2), respectively, over a surface coverage range of 0-8%. The computed contributions to surface energy values were found to match closely with data collected on macroscopic crystals by alternative techniques (+/-<1.5 mJ/m(2)).