Porous Layer Open-tubular Capillary Column Research Articles

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. Aqueous injections will not harm the column.

A porous layer open-tubular capillary column supported with pepsin and zeolitic imidazolate framework for enantioseparation of four basic drugs in capillary electrochromatography

New material zeolitic imidazolate framework-4, 5-imidazoledicarboxylic acid (ZIF-IMD) located on the pore surface of porous layer open-tubular (PLOT) column previously functionalized with N-(3-aminopropyl)-imidazole have been prepared via a layer-by-layer self-assembly strategy. This new ZIF-IMD coating hybrids are used as solid-phase carriers for chiral selector pepsin immobilization. The ZIF-IMD material was characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscope and X-ray diffraction. The synthesized pepsin@ZIF-IMD@POLT column achieved the baseline separation of hydroxychloroquine (HCQ), chloroquine (CHQ) and hydroxyzine (HXY) (the resolution of HCQ: 2.19; CHQ: 1.84; HXY: 1.53). Compared with the pepsin@PLOT column (without ZIF-IMD material), the chiral separation capability of the pepsin@ZIF-IMD@POLT column can be remarkably improved. Several key parameters including concentration of chiral selector, buffer pH, applied voltage and buffer concentration were systematically evaluated to provide the optimal enantioseparation condition. The relative standard deviations (RSDs) of intra-day, inter-day, column-to-column and inter-batch of migration time and Rs of the HCQ were evaluated in detail, respectively (RSD < 7.21%). Additionally, the potential mechanism of increased resolution was discussed in the article.

A porous layer open-tubular capillary column with immobilized pH gradient (PLOT-IPG) for isoelectric focusing of amino acids and proteins

A porous layer open-tubular capillary column with immobilized pH gradient (PLOT-IPG) was prepared in two steps. First, a partially filled porous layer open tubular capillary column containing active epoxy groups was synthesized by in situ polymerization of acrylamide, glycidyl methacrylate, and N,N′-methylenebisacrylamide. Then, an aqueous solution of commercial carrier ampholytes (CAs, Pharmalyte) was focused in the prepared polymer column. With the column immobilized by Pharmalyte 4.5–6.0 (narrow pH range) or Pharmalyte 3.0–10.0 (wide pH range), proteins with known pIs were separated and a good linear correlation between pI values and migration times was obtained. Meanwhile, resolution was improved compared to the traditional gradient with a wide pH range. A mixture of low molecular weight amino acids was separated with the narrow pH range PLOT-IPG column; from the obtained results, the resolution of our new column was calculated to be at most 0.09 pH unit. In addition, human serum proteins were analyzed with the newly developed wide and narrow pH range PLOT-IPG columns; its sensitivity and resolution in the narrow pH range one were better than capillary electrophoresis.

Preparation and Application of Porous Layer Open Tubular Capillary Columns with Narrow Bore in Liquid Chromatography

In recent years, micro/nano-scaled separation technique has attracted increasing attention due to its inherent advantages. The porous layer open tubular (PLOT) capillary column is an important micro-column form. Compared to wide-bore PLOT capillary columns (inner diameter > 25 μm), the PLOT capillary columns with narrow inner diameters yield higher separation efficiencies and lower reagent consumption. In this paper, the preparation methods for porous layer open tubular capillary columns with narrow inner diameters, less than or equal to 25 μm, are reviewed. Detection techniques combined with mass spectrometry and their applications in liquid chromatography are also discussed.

Porous layer open tubular monolith capillary column: switching-off the reaction kinetics as the governing factor in their preparation by using an immiscible liquid-controlled polymerization

A new approach for preparation of monolithic porous layer open-tubular capillary columns that eliminates the need for incomplete polymerization is presented. By expelling monomers from the capillary with a completely immiscible liquid a thin layer of polymerization mixture that wets the wall is left and polymerized by UV light.

Evanescent wave-initiated photopolymerisation as a new way to create monolithic open-tubular capillary columns: use as enzymatic microreactor for on-line protein digestion

Evanescent wave-initiated photopolymerisation in an optically wave guiding PTFE-coated fused silica capillary using light-emitting diode as a light source, is established here as a way to fabricate monolithic porous layer open-tubular capillary columns with a potential in capillary separation methods; application of the obtained open-tubular columns as enzymatic microreactors for on-line protein digestion is demonstrated.

The Influence of Temperature on the Gas Chromatographic Retention of n-Alkanes, Arenes, and Alkanols in a PLOT Capillary Column with Aerosil

Adsorption and chromatographic properties of a porous-layer open-tubular (PLOT) capillary column with aerosil were studied. The retention factors k of n-alkanes, not condensed and condensed arenes, and alcohols were determined over the temperature range 120–180°C, and the heats of their adsorption were calculated. The Rohrschneider constants (100°C) and the contributions of specific interactions to the adsorption heats were determined. It was shown that the PLOT/SiO2 column was similar in chromatographic properties to wall coated open tubular columns with polysiloxane stationary phases but superior to them as concerns thermal stability and service life.