ELUTION BEHAVIOR OF CHEMICALLY DIFFERENT PROBES ON THE EVALUATION OF SURFACE-PROPERTIES OF CELLULOSE BY INVERSE GAS-CHROMATOGRAPHY

The inverse gas chromatography (IGC) technique has been employed to ex amine adsorption behavior of cellulose surfaces from elution character istics of chemically different adsorbates. The neutral probes were elu ted completely during IGC measurements while acidic, amphoteric, and b asic probe molecules were eluted incompletely. In this work, complete elution is defined by the hat postpeak FID signal within the noise lim its of the detector. An understanding of incomplete elution is thereby reached by introducing a precisely controlled, very small quantity of individual probes into the column. A strong correlation is found betw een elution efficiency of vapors and their enthalpies of acid-base int eractions. Delayed elution of acid-base vapors is interpreted as being due to nonequilibrium sorption process, and calculations have shown t hat diffusion into the bulk is unlikely under the measurement conditio ns. The chromatographic process is simulated and it is found that the contribution of nonequilibrium adsorption to the retention is responsi ble for observed peak tailing and thereby delayed elution of acid-base probes. Results of the study indicate that characterization of acid-b ase (electron acceptor-donor) type of stationary phase material surfac es by IGC needs careful attention and is an area for future work. (C) 1997 Academic Press.