Overview of the gas phase retention volume behavior of organic compounds on polyurethane foam

Abstract

There is a need to be able to predict the compound-dependent volumes of gas that can be sampled with little breakthrough using porous polyurethane foam (PUF). Gas/solid sorption theory predicts that the specific retention volume per gram of sorbent at temperature T( K) ( V g. T. , m 3 g −1) should correlate with the vapor pressure of the pure compound ( p T o -, torr) at T. For compounds that are solids at the T of interest, the vapor pressure of the sub-cooled liquid ( p L o, T ) should be used. For polyether-type PUF that has a density of ~ 0.022 g cm −3, regressions of available data lead to the following correlation equations: (1) polycyclic aromatic hydrocarbons, log V g,293 = −1.195 log p L,293 o −1.884 ( r 2 = 0.989); and (2) organochlorine compounds, log V g,293 = −1.059 log p L,293 o −1.764 ( r 2 = 0.950). These equations will be useful in predicting retention volumes for compounds whose behavior on PUF have not as yet been studied. If the entropy of desorption for a given compound from PUF is equal to the entropy of desorption from the pure form of the compound, then the'available data indicate that the difference between the enthalpy of desorption from PUF and the enthalpy of vaporization of the pure compound is about 6 kcal mol −1 for both the PAHs and the organochlorine compounds.