Inverse gas chromatography applications: A review

Inverse gas chromatography (IGC) is a versatile, powerful, sensitive and relatively fast technique for characterizing the physicochemical properties of materials. Due to its applicability in determining surface properties of solids in any form such as films, fibres and powders of both crystalline and amorphous structures, IGC became a popular technique for surface characterization, used extensively soon after its development. One of the most appealing features of IGC that led to its popularity among analytical scientists in early years was its similarity in principle to analytical gas chromatography (GC). The main aspect which distinguishes IGC experiments from conventional GC is the role of mobile and stationary phases. Contrary to conventional GC, the material under investigation is placed in the chromatographic column and a known probe vapour is used to provide information on the surface.     

Structural organization of ethyl esters based on hexafluoropropene oxide oligomers: Inverse gas chromatography study

Samples of ethyl esters of perfluorinated acids based on hexafluoropropene oxide oligomers with molecular masses of 2000, 3100, and 4500 are used as stationary phases, and their interactions with low-molecular-mass compounds (sorbates) of different natures are studied by inverse gas chromatography. The linear dependence of the specific retention volumes for alkanes, cyclohexane, aromatic hydrocarbons, tetrachloromethane, and trifluorotrichloroethane (CFC-113) on inverse molecular masses of the oligomer samples is ascribed to the quasi-biphasic structure of the liquid oligomers. The experimental dependences of specific retention volumes on inverse molecular masses of oligomer samples make it possible to estimate the main thermodynamic characteristics of sorbate interaction with individual quasi-phases and their solubility parameters directly related to the cohesion-energy density.     

Inverse gas chromatography in the examination of modified fillers

Dispersive and specific surface properties of silica modified with silanes, titanium and zirconium coupling agents were characterised by means of inverse gas chromatography. This method was also successfully applied in the examination of raw and modified silicates.     

Inverse gas chromatography as a source of physiochemical data

Inverse gas chromatography (IGC) is presented as a useful method for the examination of physicochemical properties of various materials. The advantages of IGC are presented. However, the uncertainties and sources of possible errors are also indicated and discussed.     

Inverse gas chromatography for the study of one phase and two phase polymer mixtures

Experiment finds that, for a chlorinated polyethylene (chlorine content 62.1% by weight)/poly(ethyl methacrylate) blend, a negative value of χ′_{2 3} is obtained, which indicates compatibility. With increasing temperature, χ′_{2 3} increases towards zero as required by the lower critical solution temperature behaviour of polymer blends. For chlorinated polyethylene/poly(butyl acrylate) blends however the specific retention volume is a linear function of composition and a positive χ′_{2 3} results if calculated by the conventional theory. The magnitude of χ′_{2 3} is determined by the difference between the retention volumes of the pure polymers and decreases with temperature. This effect is assumed to be a result of phase separation during coating the blend onto the support. A theoretical treatment is developed to explain this behaviour.     

Identification of stilbene derivatives by paper and gas chromatography and paper eleetrophoresis

Summary Some stilbene derivatives have been identified by using paper chromatography in five different solvents systems, paper electrophoresis in two different electrolytes, and gas chromatography to detect cleavage products.

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Zusammenfassung Einige Stilbenderivate wurden chromatographisch mit fünf verschiedenen Lösungsmittelsystemen identifiziert, elektrophoretisch in zwei verschiedenen Elektrolyten und gaschromatographisch unter Nachweis der Spaltprodukte.

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Résumé On a identifié quelques dérivés du stilbène par Chromatographie sur papier dans 5 systèmes différents de solvants, par électrophorèse (sur papier) dans deux électrolytes différents et par Chromatographie en phase gazeuse pour déceler les produits de coupure.

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Dedicated to the 60th birthday of Prof. Dr.M. Jureek, Dr. Sc.     

Inverse gas chromatography of poly(cyclohexyl methacrylate)

Inverse gas chromatography is applied to determine the glass transition temperature T_g of poly-(cyclohexyl methacrylate). Both good and bad solvents for the polymer are used as molecular probes. Although the transition is clearly detected by both types of probes, only the nonsolvents yield a T_g in quantitative agreement with the value determined by differential scanning calorimetry. The relative depth of penetration of the probe in the polymer phase is calculated from retention volume data. Also, the height equivalent to a theoretical plate is calculated from peak halfwidths. Both calculated magnitudes show a temperature dependence which significantly differs from good to bad solvents. Some kind of diffusion-limited penetration of the probe in the bulk of the glassy polymer may be responsible for the difference.     

Inverse gas chromatography as a tool for investigation of nanomaterials

Inverse gas chromatography (IGC) is presented as a representative tool for the investigation of nanomaterials: Aerosil200V and two iron oxides (nanohematite and nanogoethite). IGC was used for characterization of the surface properties of materials. Parameters describing their surface properties are calculated from the retention data of test solutes injected into a column filled with the solid of interest. It is possible to determine the surface activity and the Hamaker constants of different nanomaterials.     

Studies on paper chromatography

Conclusion A study with filter paper strips partially impregnated with the precipitating agent with or without colloid as the fixing agent reveals that in the case of spotted strips run in aqueous alcoholic mixture as the solvent, uniform bands of the precipitate are formed. In these cases, chromatographic observations such as measurement of S and R_f values is possible. Rhythmic structures can also be obtained with these strips when the reactant solution is used as the solvent. In the absence of colloids rhythmic structures are obtained at a high concentration and the bands obtained have to be washed and repeatedly dipped in hot water in order to clear the structure of rings present underneath. In the presence of colloid, rhythmic vertical bands are obtained at a much lower concentration and the clear interspaces are visible even without washing. Thus an independent method for obtaining rhythmic structures on filter paper with a technique very similar to chromatography has been developed.Part I see Z. analyt. Chem. 149, 339 (1956).     

Electro chromatography on paper

The term 'electrochromatography' is used to denote the specific cases where chromatography and ionophoresis operate simultaneously. The electric field may be applied either in the direction of flow of the solvent or at right angles to it. The filter paper is previously treated with the relevant buffer solution and the developing solvent too is saturated with it. Colloidal graphite painted on the two sides of the paper serves as electrodes.A detailed study has been made of a number of amino acids at different pH's with phenol-buffer as the developing solvent. On ordinary paper acidic amino acids move towards the anode, basic ones towards the cathode, neutral amino acids do not move at all. Using buffer-treated papers, however, the movement depends upon the pH of the buffer and the isoelectric points of the amino acids. By choice of suitable pH and application of electric field in proper direction amino acids having very close RF values (except isomers) can be separated from one another.     

Studies on paper chromatography

Zusammenfassung In Gegenwart von Komplexon tritt durch Bildung eines gefärbten Komplexes zwischen Zirkonium und dem Reagens Brenzcatechinviolett eine tiefblaue Färbung auf. Nahezu alle störenden Ionen werden durch Komplexon maskiert. Nur Sb^III und Sn^IV sind abzutrennen, was in Gegenwart von Komplexon mit Ammoniak leicht vor sich geht. Die Empfindlichkeit wird durch die meisten Kationen bis zu Grenzkonzentrationen l1000 nicht beeinflußt und beträgt 0,6 [A] 0,03, pD=4,7. Komplexbildende Anionen stören. Die Störung durch Fluorid-Ion kann jedoch mittels Berylliumzugabe ausgeschaltet werden.Den Firmen Riedel-de Haën, Seelze/Hann., und B. Siegfried, Zofingen, Schweiz, danken wir herzlichst für die Überlassung von Chemikalien.     

Inverse gas chromatography analysis of spruce fibers with different lignin content

Unbleached TMP spruce fibers were stepwise delignified by KMnO₄/H₂SO₄ and five partly delignified samples were obtained. Fibers were characterized in terms of carboxylic groups, lignin and hemicelluloses content. IGC measurements were performed in the untreated fibers and in the five delignified fiber samples, as well as in microcrystalline cellulose (MCC). Different parameters, such as the dispersive component of the surface free energy (g_s ^d \gamma_{{_{s} }}^{d} ), the free energy and the enthalpy of adsorption with nonpolar probes ( \Updelta G_a^d \Updelta G_{a}^{d} and \Updelta H_a^d \Updelta H_{a}^{d} , respectively), as well as the specific interactions with polar probes, quantified by the free energy and the enthalpy of adsorption ( \Updelta G_a^s \Updelta G_{a}^{s} and \Updelta H_a^s \Updelta H_{a}^{s} , respectively), were determined. The values of g_s ^d \gamma_{{_{s} }}^{d} and \Updelta G_a^d \Updelta G_{a}^{d} are for all samples lower than for pure cellulose and vary slightly with the amount of lignin. For small contents of lignin, the values of \Updelta G_a^s \Updelta G_{a}^{s} of the acidic probes decrease with the delignification whereas those of the basic probes increase, pointing to a rather acidic character of the fibers due to the increase of the relative amount of the carbohydrates. The values for MCC corroborate these findings. Despite the substantial variation in the carboxylic group content during delignification, no clear tendencies were detected regarding the affinity with the basic probes.     

Purification and analysis of partially alkylated cyclodextrins by liquid and gas chromatography

Complex mixtures of partially alkylated cyclodextrins can be analyzed by both HPLC and high temperature capillary GC. Because of the limited efficiency of LC, suitable analytical and preparative separations can be achieved only with systems of carefully optimized selectivity. Using LC it has been possible to isolate and purify single cyclodextrin species from very complex mixtures of components which contain unreacted hydroxyl groups in addition to the alkoxy groups. Analysis of the reaction mixtures and of fractions taken from LC separations can be performed with advantage by high resolution capillary GC at high temperatures between 300 and 400 °C. The thermal stability of partially alkylated cyclodextrins in high temperature GC is considerably increased by trimethylsilylation of the free hydroxyl groups. Fast atom bombardment mass spectrometry and proton NMR were used to identify species isolated from the preparative LC separations.     

High-temperature separation with polymer-coated fiber in packed capillary gas chromatography

High-temperature gas chromatographic separation of several synthetic polymer mixtures with Dexsil-coated fiber-packed columns was studied. A bundle of heat-resistant filaments, Zylon, was longitudinally packed into a short metal capillary, followed by the conventional coating process with Dexsil 300 material. Prior to the packing process the metal capillary was deactivated by the formation of a silica layer. The typical size of the resulting column was 0.3-mm i.d., 0.5-mm o.d., 1-m length, and packed with about 170 filaments of the Dexsil-coated Zylon. The column temperature could be elevated up to 450°C owing to the good thermal stability of the fiber, Dexsil coating, and metal capillary; furthermore, this allowed the separation of low-volatile compounds to be studied.     

Inverse gas chromatography in the study of polymer degradation. Part 4: A study of model systems for reinforced vulcanizates

Summary Inverse gas chromatography with olefinic stationary phases, impregnated with silica gel or carbon black, and air as carrier gas has been found to yield characteristic shifts of retention data and concomitant changes in peak shape. The plots of retention index versus oxygen flow obtained indicate carbon black to have significant antioxidant properties, which are not altogether lost on solvent extraction. On the other hand, silica gel yields results consistence with the existence of a novel chain scission repair process.     

Analysis of free and esterified sterols in fats and oils by flash chromatography, gas chromatography and electrospray tandem mass spectrometry.

A method for the analysis of free and esterified sterols has been developed. Fat or oil samples were separated on solid-phase extraction silica gel columns into a sterol ester fraction, a fraction of triacylglycerols, and a free sterol fraction containing partial acylglycerols and residual triacylglycerols. Sterol esters and acylglycerols of the free sterol fraction were transesterified to methyl esters. The fatty acid methyl esters from sterol ester fraction and the free sterols from sterol ester fraction and free sterol fraction were determined by GLC. Precursor ion electrospray MS-MS of sterol fragment ions of sterol ester fractions were recorded and used for determination of sterol ester proportions in butterfat and vegetable oil samples.     

Inverse gas chromatography and other chromatographic techniques in the examination of engine oils

The emerging market of engine oils consists of a number of products from different viscosity and quality classes. Determination of the base oil used in manufacturing of the final product (engine oil) as well as estimation of mutual miscibility of oils and their solubility could be crucial problems. Inverse gas chromatography and other chromatographic techniques are presented as an interesting and fruitful extension of normalised standard analytical methods used in the oil industry.