Sol-Gel Synthesis of Chelate Containing Materials for Gas Chromatography

The adsorption properties of mesoporous chelate containing sorbents which were prepared in two phases with europium and copper acetylacetonate complexes and PEG-115 as surfactant, were evaluated by column experiments.The adsorption properties of mesoporous silica with chelate complexes for some organic compounds were evaluated by gas chromatography. The best separation was achieved for europium acetylacetonate. From specific retention volumes measured at various temperatures the thermodynamic parameters of separation is discussed. Mutual separation of oxygen containing substances could also be demonstrated.

Evaluation of a Hypercrosslinked Polystyrene, MN-200, as a Sorbent for the Preconcentration of Volatile Organic Compounds in Air

Breakthrough volumes, average percentage recoveries, and storage stabilities were obtained for vapors of 8 volatile organic compounds (pentane, octane, undecane, isooctane, cyclohexane, toluene, methanol, and dichloromethane) on a new adsorbent material, Hypersol-Macronet, MN-200. Breakthrough volumes were estimated as half of the gas chromatographic specific retention volumes at 20°C for the compounds. Recoveries of the adsorbates were determined by both solvent extraction and thermal desorption methods. The results obtained compare favorably with those for Tenax GR (values reported in the published literature and others obtained in our laboratory). Results of storage stability studies on MN-200 meet the criterion for acceptability (<10% loss). High adsorption capacity for very volatile and polar compounds, combined with ease of desorption of less volatile compounds, render MN-200 a highly promising adsorbent for sampling volatile organic compounds in indoor and outdoor air.

Adsorption of Vapours of Some Organic Compounds on Surface of Iron-Substituted Layered Vanadyl Phosphate

Gas chromatographic measurement of specific retention volumes of vapours of selected groups of organic compounds has been used to determine differential molar enthalpy of adsorption of their molecules on the surface of layered vanadyl phosphate substituted with ferric ions having the composition of [Fe(H2O)]0.20(VO)0.80PO4. Various types of bonds of the molecules to the surface of the layered adsorbent including their probable orientation with respect to the layers have been discussed. It was observed a dependence of the specific peak elution volume and shape of chromatographic peak on the sample size in the cases of those compounds whose molecules are chemically bound to the adsorbent surface. A connection is pointed out between the adsorption strength of the organic molecules on the layered adsorbent and the tendency of the system to undergo intercalation reaction.