IGC investigation of the effect of the length of the n-alkyl substituent in 5-alkylsubstituted norbornenes on solute retention.

Polymerization of 5-n-alkyl-substituted 2-norbornenes synthesized a series of polymers having the same structure of the main polymer chain, but differing in the length of the alkyl substituent (up to 14 methylene units). The obtained polymers were studied by the capillary IGC method as a stationary phase during separation of a mixture of normal hydrocarbons C6-C10. Retention data in the form of a logarithm of the retention factor lnk were correlated with the size of the sorbate (via the carbon number of the alkane Z) and with the size of the n-alkyl substituent in the polymer chain (via the carbon number of the polymer Z).

Impact of the Polymer Backbone Structure on the Separation Properties of New Stationary Phases Based on Tricyclononenes.

The main purpose of this paper is to compare the chromatographic properties of capillary columns prepared with polymers with different backbone structures and to demonstrate the possibility of polymer differentiation via inverse gas chromatography. With the use of addition and metathesis types of polymerization of tricyclononenes, two new stationary phases were prepared. The metathesis polymer contained double bonds in the polymeric backbone while the backbone of the addition polymer was fully saturated and relatively mobile.

Preparation and properties of GC capillary column with hypercrosslinked stationary phase.

For the first time, highly porous hypercrosslinked polystyrene layer was synthesized within a gas chromatography capillary column and successfully deposited onto the capillary walls generating porous layer open-tubular capillary column. Elaborated three steps synthetic procedure provides tightly bonded porous polymeric layer and ensues complete elimination of particle shedding and the needs for particle traps. Due to highly developed surface area, porous layer open-tubular column provides strong solute retention that is useful for the separation of various volatile solvents and light gas compounds including ethane, ethylene, ethyne.

Chromatographic Method for Evaluation of Polymeric GC Stationary Phases Ageing Using the Novel Non-Cross-Linked Poly(3-(Tributoxysilyl)Tricyclononene-7) as the Model Stationary Phase.

The chromatographic properties and thermal stability are investigated for the polymeric stationary phase based on the norbornene polymer. It was shown that without additional cross-linking, poly(3-(tributoxysilyl)tricyclononene-7) demonstrates properties similar to liquid chromatographic stationary phases. It was also found to be more thermally stable than previously studied trimethylsilyl- and trimethoxysilyl- derivatives.

The Stability Study of Thermodynamic Parameters of Sorption of Light Hydrocarbons on Poly [Trimethylsilyl (Propyn-1)] at Different Temperatures.

Chromatographic determination of the thermodynamic parameters of sorption for light hydrocarbons retention on a stationary phase based on poly [trimethylsilyl (propyn-1)] (PTMSP) was performed and the effect of column preheating at temperatures up to 260°C on the retention of analytes was investigated. It was shown that heating the column to 130°C does not affect the retention of the analytes. At temperatures above 130°C, the gradual decrease of the retention of analytes on PTMSP stationary phase is observed.

Monolithic thin-layer chromatography plates with covalently bonded matrix for hyphenation with matrix-assisted laser desorption/ionization.

Monolithic layers prepared by the copolymerization of ethylene dimethacrylate and glycidyl methacrylate and deposited onto the surface of glass and silicon plates were investigated as thin-layer chromatography separation media in hyphenated thin-layer chromatography with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. Varying composition of the polymerization mixture and polymerization conditions layers of different porosities and MALDI-MS compatibility were synthesized. Compatibility with MALDI-MS was tested using polyethylene glycol and it was demonstrated that layers prepared without glycidyl methacrylate are not compatible with MALDI-MS and do not allow obtaining any mass spectra.

Recent advances in the preparation of adsorbent layers for thin-layer chromatography combined with matrix-assisted laser desorption/ionization mass-spectrometric detection.

This review is focused on planar chromatography hyphenated with mass-spectrometric detection for analysis of low-molecular-mass solutes. Various kinds of hyphenations are discussed with attention paid to the preparation of thin layer plates suited both for the mass-spectrometric detection of the resolved solutes direct from thin-layer plates and for indirect mass-spectrometric detection of the resolved solutes, performed by scraping, extracting, purifying, and concentrating the analyte from the thin-layer chromatography plate. Plates with monolithic layers are relatively new for thin-layer chromatography but they can successfully be combined with mass-spectrometric technique in a pursuit of comprehensive local sample composition information.

Thermal stability of poly[1-(trimethylsilyl)-1-propyne] and the gas chromatographic stationary phase based on it.

The thermal stability of poly[1-(trimethylsilyl)-1-propyne] is investigated by heating the capillary column with this polymer as the stationary phase with the subsequent separation of the test mixture of light hydrocarbons. It is shown that heating of the column up to 130°C does not cause a decrease in efficiency or in the retention time of solutes. A further increase in temperature results in both decrease in column efficiency and sorbate retention.

Extrathermodynamic parameters of sorption of light hydrocarbons on stationary phases prepared from tricyclononene polymers.

Enthalpy and entropy of adsorption of polar and non-polar solutes were measured by chromatographic technique for new stationary phases prepared from membrane polymers based on tricyclonones. Data obtained within temperature interval from 40 to 150 °C were used to create extrathermodynamic dependences (compensation plots, dependences of enthalpy and entropy changes on solute carbon number). Compensation plots were very similar for all the stationary phases indicating similar adsorption mechanisms.

New stationary phases for gas chromatography based on polymers with intrinsic porosity.

Norbornene polymers with intrinsic porosity were investigated as candidates for polymeric stationary phases in capillary GC. Kinetic and thermodynamic characteristics of the stationary phases were evaluated and turned out that only polymer with vicinal distribution of trimethylsilyl groups (polymer II) provided properties making it potential candidate for application in capillary GC. Columns with stationary phase based on polymer II demonstrated unique selectivity, moderate thermostability and efficiency better than previously studied columns with stationary phase based on poly[(1-trimethylsilyl)-1-propine].

Investigation of poly[oligo(ethylene glycol)diacrylates] as potential stationary phases in GC.

Poly[oligo(ethylene glycol)diacrylate]s were investigated as potential candidates for application as stationary phases in capillary gas chromatography. Depending on the molar mass of the monomer, up to three different phase transitions were observed in calorimetric scans of the polymers. Two transitions have been identified as the glass transition and melting of crystallites while the nature of the third effect remains unknown.

Kinetic performance of stationary phases for gas chromatography based on poly(oligoethyleneglycoldiacrylate).

Open capillary columns with polymeric stationary phases based on poly(oligoethyleneglycoldiacrylate) were prepared and tested on their kinetic performance. Stationary phases prepared with low molar mass monomers were inferior to stationary phases based on high molar mass monomers. Structure of these stationary phases appeared to be favorable for solute diffusion in the stationary phase.

Application of kinetic plots in gas and liquid chromatography for the optimization of separation conditions.

This review describes the recent achievements and historical background of investigations in optimization procedures in gas and liquid chromatographic techniques. The optimization parameters are varied depending on researcher interests and may include separation efficiency, analysis time, column operation pressure, packing characteristics, etc. As it is shown the kinetic performance limit is one of the most used and vital concepts for gas and liquid chromatography.

[Hydrocarbon-Oxidizing potential and the genes for n-alkane biodegradation in a new acidophilic mycobacterial association from sulfur blocks].

Capacity of AG(S10), a new aerobic acidophilic (growing within the pH range from 1.3 to 4.5 with the optimum at 2.

Monolithic capillary columns based on pentaerythritol acrylates for molecular-size-based separations of synthetic polymers.

Monolithic capillary columns based on pentaerythritol triacrylate and pentaerythritol tetraacrylate were synthesized using different compositions of polymerization mixtures and different polymerization conditions. The impact of porogen type and porogen/monomer ratio on the porosity of synthesized monoliths was investigated. Porogen type appears to be the main factor influencing the separating properties of the monolithic sorbent.

Kinetic efficiency of polar monolithic capillary columns in high-pressure gas chromatography.

Poppe plots were used for analysis of kinetic efficiency of monolithic sorbents synthesized in quartz capillaries for utilization in high-pressure gas chromatography. Values of theoretical plate time and maximum number of theoretical plates occurred to depend significantly on synthetic parameters such as relative amount of monomer in the initial polymerization mixture, temperature and polymerization time. Poppe plots let one to find synthesis conditions suitable either for high-speed separations or for maximal efficiency.

Monolithic column in gas chromatography.

Monolithic columns invented in chromatographic praxis almost 40 years ago gained nowadays a lot of popularity in separations by liquid chromatographic technique. At the same time, application of monolithic columns in gas chromatography is less common and only a single review published by Svec et al. covers this field of research.

Separation of polystyrenes by means of open tubular capillary chromatography.

Simulating polymer separation in flow-through channels of monolithic columns, separation of a mixture of polystyrene standards was investigated using open tubular capillary column of 2 μm inner diameter. High column efficiency was observed for polymers of molar mass ranged from few tens to few hundred kDas. Column efficiency significantly decreased for polymers with molar mass larger than 500 kDa nevertheless preserving value of few tens of thousands theoretical plates.

Monolithic columns with optimized pore structure for molecular size-based separations of synthetic polymers.

Monolithic capillary columns based on divinylbenzene were synthesized using different alcanols as porogens. Prepared columns were tested in separation of polystyrene standards according to their molar mass (MM) and were characterized by corresponding calibration graphs. It was demonstrated that a decrease of alcanol chain length from dodecanol to octanol resulted in a decrease of column permeability and in an improved column ability to separate polystyrene standards.

Enthalpy-entropy compensation effect on adsorption of light hydrocarbons on monolithic stationary phases.

Enthalpy and entropy of adsorption of light hydrocarbons C1-C4 have been measured for three monoliths of different polarity and for five different carrier gases: helium, hydrogen, nitrogen, carbon dioxide and dinitrogen oxide. Using carrier gas helium the highest values of enthalpy and entropy were observed for monolith based on ethylenedimethacrylate and the lowest values were observed for monolith based on silica, while monolith based on divinylbenzene demonstrated intermediate values. Entropy-enthalpy correlations were observed with carrier gas helium for all thee monoliths and possess similar slope indicating similar adsorption mechanism on all monoliths studied.

Optimization of performance of monolithic capillary column in gas chromatographic separations.

Dependence of monolithic column efficiency on column pressure was analyzed using modified Van Deemter relationship with incorporated inlet and outlet column pressures as independent variables. It was demonstrated that the highest column efficiency is observed at high pressures. Inlet and outlet pressure increase has to be controlled in such a way that the relative pressure approaches 1 and the pressure drop across the column is close to zero.

Characterization of monolithic capillary columns using inverse gas chromatography.

Polymeric monoliths of different polymeric natures and different degrees of cross-linking were prepared in capillaries of inner diameter 100 microm. The properties of the monoliths prepared were investigated by means of inverse gas chromatography. Solubility coefficient S, Flory-Huggins parameter chi(12)(infinity), and reduced Flory-Huggins parameter chi(12)(infinity') were evaluated.

Comparison of nonporous silica-based ion exchangers and monolithic ion exchangers in separations of inorganic anions.

Low capacity anion exchangers for IC have been prepared by modification of nonporous uniformed silica MICRA microbeads and by modification of the organic polymeric monolithic matrixes prepared in situ in quarz capillary. Due to the small particle size (1.5 microm) high-performance adsorbents were prepared allowing to obtain up to 190,000 tp/m.

Less common applications of monoliths. III. Gas chromatography.

Porous polymer monoliths emerged about two decades ago. Despite this short time, they are finding applications in a variety of fields. In addition to the most common and certainly best known use of this new category of porous media as stationary phases in liquid chromatography, monolithic materials also found their applications in other areas.