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Application Note 202 – Determination of the dispersive surface energy of Paracetamol
by pulse inverse gas chromatography at infinite dilution.
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Application Note 204 – Determination of the glass transition temperatures Tg of maltose
and its dependence on relative humidity by infinite dilution inverse gas chromatography.
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Application Note 215 – A sorption study on microporous materials by finite dilution inverse gas chromatography. pdficon_small pdf
Application Note 216 – Characterisation of surface properties of glass fibres by inverse gas
chromatography.
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IGC Application Note 201 Polymorphism in Spray Dried Lactose – Gas diffusion effects become stronger at lower rates of flow as evidenced experimentally by IGC peak shapes.  At higher flow rates equilibrium cannot be assumed and adsorption will be less than at equilibrium state.  This application note shows how to find a compromise between the two.  Elution studies were performed on alpha-Lactose-Monohydrate with cyclohexane in the infinite dilution range.
IGC Application Note 203 Heat of sorption studies on micro crystalline cellulose by pulse inverse gas chromatography at infinite dilution – Inverse gas chromatography provides a fast and accurate method to measure the heat of sorption over different concentration and temperature ranges. Moreover iGC SEA also allows the study of this parameter at different relative humidities. This paper describes the determination of the heat of desorption of octane on microcrystalline cellulose at infinite dilution and two different humidities.
IGC Application Note 205 The determination of the solubility parameter of different starch types by infinite dilution inverse gas chromatography – Solubility parameters are directly related to the cohesive energy density of a material. The latter is a measure for the strength of interaction between molecules and atoms; therefore, the solubility parameter can be used to predict the stability of food ingredients, polymers, drugs or excipients. Inverse Gas Chromatography provides a fast and sensitive route for the measurement of this parameter. This paper describes the determination of the solubility parameter of starch measured by water at infinite dilution
IGC Application Note 206 Determination of permeability coefficients of alkanes in polyethylene powder by infinite dilution inverse gas chromatography – The diffusion of solvent molecules in polymers can be measured rapidly and accurately by IGC at any concentration. At infinite dilution the van Deemter equation can be applied to obtain bulk diffusion coefficients. This paper demonstrates the performance of IGC measurements for the diffusion of octane in polyethylene.
IGC Application Note 207 Characterisation of drug polymorphs by inverse gas chromatography – Two polymorphs of the same active pharmaceutical material were characterised by infinite dilution inverse gas chromatography. Clear differences were observed in the surface properties despite the chemically identical nature of the samples. The sensitivity of the technique may be of considerable use in the identification of batch-to-batch variations, polymorphic forms being one cause of this problem.
IGC Application Note 208 The measurement of isotherms by pulse inverse gas chromatography – Isotherm measurements provide the means to calculate BET surface areas and pore size distribution functions. Standard measurements at 77 K are restricted to very few probe molecules. Moreover, these temperatures cause long measurement times despite that they are less relevant in practical terms. Inverse Gas Chromatography provides a fast and accurate isotherm measurement in a wide temperature range and with various probe molecules. This is demonstrated in this paper by hexane and cyclohexane sorption measurements on different oxides.
IGC Application Note 209 An investigation of Chromosorb silicas as support materials for inverse gas chromatography – Chromosorb materials are interesting candidates for the support of viscous liquids in inverse gas-solid and gas-liquid chromatography. The tests conducted in this study include the determination of the material surface energy and its specific interaction with a range of polar probes.
IGC Application Note 210 Investigation of the influence of bleaching conditions on surface properties of standard hair samples by inverse gas chromatography – The surface energy is a useful parameter describing the energetic properties of the surface of a solid sample. It can be determined in a fast and accurate way by inverse gas chromatography (IGC SEA). This paper describes the application of this approach for the investigation of how different bleaching conditions can cause changes on the surface of standard hair samples.
IGC Application Note 211 An investigation of minerals used in asphalt by inverse gas chromatography – The affinity of minerals to bitumen is highly important for the quality of the asphalt composition. In order to predict this affinity a detailed knowledge of the physico-chemical properties of the mineral surface is required. Inverse Gas Chromatography (IGC SEA) is a fast and sensitive method for the characterisation of solid powders. In the current study dispersive as well as acid-base properties have been investigated for different minerals.
IGC Application Note 212 The characterisation of amorphous materials by inverse gas chromatography – The amorphous state of differently processed lactose samples has been studied by Inverse Gas Chromatography at infinite dilution. The dispersive surface energy was taken as a measure for the energetic state of the samples. Significant differences were found independent of particle size and amorphous content. The observed differences confirm distinctive amorphous states although the experiments allow no conclusion as to whether or not this is due to poly-amorphism. The varying changes in surface energy with amorphous content further suggest that the location and distribution of the amorphous phase within a crystalline matrix also affects the results.
IGC Application Note 213 Determination of thermodynamic parameters by frontal inverse gas chromatography – Strongly adsorbing materials are sometimes difficult to measure by pulse IGC SEA since peaks become very broad and flat at infinite dilution conditions. An increase in temperature or concentration could change the surface thermodynamics significantly. An alternative method is the application of the frontal method at infinite dilution. This was until now difficult to realise since advanced instrumentation is required. This paper describes frontal measurements using the SMS-iGC SEA at low concentration and temperature. The heat of sorption on carbon blacks is determined as an example for a typical infinite dilution property.
IGC Application Note 214 The determination of the permeability and the activation energy of diffusion of drug powders by infinite dilution inverse gas chromatography –  IGC SEA provides an easy and quick route for the determination of diffusion coefficients of solvents in powders and films. The determination of the diffusion coefficient in drug powders is performed by applying the van Deemter approach at infinite dilution. A measurement of this property at different temperatures also provides the activation energy for the diffusion process.
IGC Application Note 215 A sorption study on microporous materials by finite dilution inverse gas chromatography – Finite concentration IGC SEA is a useful tool for the investigation of surface and pore properties. A novel combination of finite concentration IGC SEA and thermal desorption provides the possibility to separate micropore adsorption from surface and mesopore adsorption. This allows the calculation of BET values with physical relevance for highly microporous materials and the consideration of molecular sieve effects.
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