Influence of temperature on specific retention volumes of environmentally important volatile organic compounds in gas liquid chromatography

Abstract

Temperature dependence of specific retention volumes V^o_g of 13 volatile organic compounds (VOCs) of environmental importance between the gas and liquid stationary phase (polydimethysiloxane, PDMS) are presented, determined by gas chromatographic method. Activity coefficients at infinite dilution were calculated from these specific retention volumes and they are in agreement with those obtained from static headspace and group contribution methods by the authors as well as literature values. The results of this work confirm that PDMS is well suited for VOCs scrubbing from waste gas streams. The measurements were carried out at temperatures (303.15, 313.15, 323.15., 333.15, 353.15, 373.15, 393.15 and 423.15) K to allow transport calculations for different seasons. Four PDMS polymers with average molecular weight ranging from 760 to 13 000 were used as solvents. Linear plots of log V_g against ¹/_T were obtained in all cases, thus allowing for predictions at other temperatures not investigated in this study. Since the typical van’t Hoff plots were nicely linear, dependable enthalpies and entropies of solute transfer from the mobile phase to the stationary phase can also be calculated. Efforts were taken to ensure the best possible accuracy and trace the possible source of error. We devised a gas liquid chromatographic system which
secured a simple retention mechanism and showed reproducible solute retention over a long period of time.

Keywords: Specific retention volume, Waste gas streams, Stationary phase, Gas liquid chromatography, Scrubbing, Temperature dependence