Adenine-functionalized polypropylene glycol: A novel stationary phase for gas chromatography offering good inertness for acids and bases combined with a unique selectivity

End-modification of poly(ether-carbonate) copolymer by adamantane cages: An effective approach for improving the selectivity of gas chromatographic stationary phases

This work reports the investigation of a new poly(propylene-carbonate) copolymer terminated by the adamantane cages (APPC) as the stationary phase for gas chromatographic (GC) analyses. In GC, the selectivity of a stationary phase is the key factor that governs the column separation performance for analytes, particularly those of high similarity in structures and properties. As such, we employed more than a dozen of isomer mixtures of separation difficulty for investigating the separation performance of the APPC column, involving the isomers of alkanes, alkylbenzenes, halobenzenes phenols and anilines. Meanwhile, the column coated with poly(propylene carbonate) diol (PPCD) differing from APPC only in their terminal groups and two commercial columns coated with polyethylene glycol (PEG) and polysiloxane, respectively, were used as the reference columns. The separation results evidenced the distinctly advantageous performance of the APPC column over the reference columns. Moreover, the APPC column showed excellent repeatability and reproducibility with the relative standard deviation (RSD) values over the range of 0.01%-0.04% for run-to-run, 0.15%-0.28% for day-to-day and 3.4%-3.9% for column-to-column (n = 4). Its application to GC-MS analysis of the verbena essential oil demonstrated its separation advantages for a wide range of components in practical samples. Up to date, the adamantyl-terminated poly(ether-carbonate) copolymers have not been reported in any fields. Its high-resolution performance demonstrates the feasibility of adamantyl-terminated block copolymers as highly selective stationary phases for GC analyses, which offers a vast room for fundamental researches and applications.

A New Capillary Gas Chromatography Column Based on Poly(ethylene glycol) Methyl Ether-Functionalized Calix[4]arene

In this work, a novel capillary column (C4A-mPEG) with a calixarene-based polymer stationary phase (poly(ethylene glycol) methyl ether-functionalized 4-tert-butylcalix[4]arene) was designed and used for gas chromatographic (GC) separations. The C4A-mPEG capillary column, prepared by the static coating method, showed moderate polarity and a column efficiency of 2332 plates/m, determined by 1-octanol at 120 °C. The separation features of C4A-mPEG stationary phase, resulting from its unique structure and multiple molecular recognition processes with analytes, including π-π, H-bonding, dipole-dipole, and van der Waals interactions, allowed to obtain high-resolution performances for a wide range of compounds and their isomers, especially benzaldehydes, phenols, and anilines. Moreover, compared with 4-tertbutyl calix[4]arene (C4A) and polyethylene glycol (PEG) stationary phases, a higher resolving capability was also observed for the separation of toluidine and xylidine isomers.

High separation performance of carbon dioxide-based poly(ether-carbonate) copolymer for gas chromatographic analyses

This work presents the investigation of a novel CO₂-based poly(ether-carbonate) copolymer, namely poly(propylene ether-carbonate)diol (PPCD), for gas chromatographic (GC) analyses. The PPCD column exhibited column efficiency of 4000 plates/m determined by naphthalene at 120 ℃ with the retention factor 6.23. Its separation performance was investigated by adopting a wide variety of analytes and isomers, including the isomer mixtures of alkanes, substituted benzene isomers with diverse groups, phenols and anilines, and the mixtures of organic solvents of high volatility, aliphatic amines and N-heterocycles. As a result, the PPCD column displayed distinctly higher resolving capability than the commercial columns described herein and achieved high column inertness towards acidic/basic analytes without involving any deactivation procedure. Additionally, it displayed excellent separation repeatability and reproducibility with the relative standard deviation (RSD) values less than 0.01% for within-day and in the range of 0.26% - 0.36% for between-day and 3.0% - 4.1% for between-column (n = 4). Further, the PPCD column (30 m) was used to GC-MS analysis of the lemongrass essential oil and resolved more components well than the indicated commercial columns, evidencing its outstanding separation performance for analyses of complex samples. Up to date, the CO₂-based poly(ether-carbonate) copolymers are not reported in the field of chromatography. This work demonstrates their promising future as a new type of selective and inert stationary phases for practical GC analyses.

Amphiphilic triblock copolymer as the gas chromatographic stationary phase with high-resolution performance towards a wide range of isomers and the components of lemon essential oil

This work presents the investigation of using the amphiphilic triblock copolymer composed of poly(ethylene oxide)(PEO)-poly(propylene oxide) (PPO)-poly(ethylene oxide) (PEO) (denoted as EPE) as the stationary phase for gas chromatographic (GC) analyses. The EPE capillary column exhibited moderate polarity and column efficiency of 4348 plates/m determined by naphthalene at 120 °C (k = 11.52). Different from the PEG and polysiloxane homopolymers, it showed high-resolution performance towards a wide range of aliphatic and aromatic isomers in terms of polarity and acid-base properties. Particularly, the EPE column displayed distinct advantages for separating the critical isomers of alkanes, anilines and phenols and the components of the lemon essential oil over the commercial PEG and polysiloxane columns. In addition, the EPE column exhibited excellent separation repeatability and reproducibility with the relative standard deviation (RSD) values in the range of 0.03% - 0.08% for run-to-run, 0.14% - 0.61% for day-to-day and 3.1% - 4.0% for column-to-column, respectively. Moreover, the EPE column was investigated in terms of thermal stability, the minimum allowable operating temperature (MiAOT) and sample loadability. Its application to GC-MS analysis of the essential oil demonstrated its feasibility for practical analyses. This work demonstrates the promising future of triblock copolymers as a new class of selective stationary phases for GC analyses, which is barely reported up to date. The findings of this work is of important value for fundamental researches and practical applications.

Separation performance of the copolymer and homopolymer of aliphatic polycarbonate diols as the stationary phases for capillary gas chromatography

This work presents the investigation of two aliphatic polycarbonate diols (CAPC and HAPC) as the stationary phases for capillary gas chromatography (GC). The CAPC and HAPC capillary columns showed moderate polarity and high column efficiency of 3704 - 4545 plates/m measured by n-octanol and naphthalene at 120 °C. It was found that despite their similar chemical compositions, CAPC and HAPC differ largely in their selectivity towards the isomers of alkanes, methylpyridines and xylenes. As demonstrated, the CAPC column exhibits advantageous comprehensive performance over the HAPC column and the commercial PEG column. Particularly, the CAPC column exhibits higher resolving performance towards the isomers indicated above and the Grob mixture than the HAPC column. Also, it shows distinct advantages over the PEG column in separating the Grob mixture, the isomers of diethylbenzenes and cymenes, and practical analysis of chemical products and the essential oil from the leaves of Rhododendron dauricum L. Additionally, the CAPC column has excellent repeatability and reproducibility on analyte retention times with the relative standard deviation (RSD) values in the range of 0.05% - 0.08% for run-to-run, 0.12% - 0.19% for day-to-day and 2.6% - 4.9% for column-to-column, respectively. Its applications to purity test of chemical products and GC-MS analysis of the essential oil demonstrate its promising future for practical GC analyses.

A novel column modification approach for capillary gas chromatography: combination with a triptycene-based stationary phase achieves high separation performance and inertness

Integration of the novel column modification approach with a triptycene-based stationary phase achieves high-resolution performance and inertness towards acids/bases and isomers for capillary GC analysis.

A novel column fabrication approach for capillary gas chromatography via a cross-linked organogel network with high stability and inertness

A new column fabrication approach for capillary gas chromatography with high column selectivity, stability and inertness.