Packed columns polymer beads

This enzyme oxidizes a- and P-anomers of D-glucose to the same extent and shows excellent stability and sensitivity about twice that for the methods with immobilized glucose oxidase. In this approach, pyranose oxidase is immobilized on tresylate-poly(vinylalcohol) beads and packed into a stainless column and peroxidase is immobilized on tresylate-hydrophylic vinyl polymer beads and packed into a transparent FITE tube that is used as the CL flow cell. The H202... 

Recent chromatographic data indicate that the interactions between the hydrophobic surface of a molded poly(styrene-co-divinylbenzene) monolith and solutes such as alkylbenzenes do not differ from those observed with beads under similar chromatographic conditions [67]. The average retention increase, which reflects the contribution of one methylene group to the overall retention of a particular solute, has a value of 1.42. This value is close to that published in the literature for typical polystyrene-based beads [115]. However, the efficiency of the monolithic polymer column is only about 13,000 plates/m for the isocratic separation of three alkylbenzenes. This value is much lower than the efficiencies of typical columns packed with small beads. 

The chromatographic procedure may be performed using a glass column (1.5 x 4 mm) packed with porous polymer beads (80 to 100 mesh) e.g., Porapack-Q and maintained at 140°C. 

Column Stainless steel size (1 M x 2 mm) adsorbent packed with porous polymer beads (60 to 80 mesh) and maintained at 120 °C. 

As the name implies, GPC or SEC separates the polymer according to size or hydrodynamic radius. This is accomplished by injecting a small amount of (100-400 fi 1) of polymer solution (0.01-0.6%) into a set of columns that are packed with porous beads. Smaller molecules can penetrate the pores and are therefore retained to a greater extent than the larger molecules which continue down the columns and elute faster. This process is illustrated in Figure 4. 

When packed into chromatography columns, TRIM beads imprinted with Boc-L-Phe were shown to have column efficiencies and separation abilities superior to ground and sieved bulk material [5]. The theoretical plate number was approximately double that obtained with conventional crushed polymer under the same conditions and the resolution of a racemate was also slightly enhanced. The difference, however, was not that great considering the additional preparation time and effort involved. 

Physical properties of porous polymer beads for packed column gas chromatography... 

According to the theory of SEC, aU partially excluded analytes elute in a relatively narrow window between the interstitial volume and the hold-up volume of the column. The interstitial volume of a column packed with a beaded material of broad bead size distribution amounts to about 40% of the column volume [144]. In addition to this volume, the mobile phase (water) also occupies the porous volume within the sorbent. In the case of our polymeric packings, the total pore volume amounted to about half of the polymer volume. AU analytes are thus expected to elute in the window between 40 and 70% of the column volume. (The size of the separation window equals the total pore volume in the column packing.) Each analyte must have a fixed position in this window corresponding to the portion of the pore volume that is accessible to its molecules. In analytical SEC, the hydrodynamic radius of a species thus can be directly read from the calibration plot showing the relationship between the analyte sizes and their elution volumes. Importandy, the distance between the elution volume of a totally excluded analyte and that of a small species of the size of a water molecule should not exceed the above one-third of the bed volume. This is the maximum separation selectivity that can be expected for the pure size exclusion mechanism of separation. 

One g of the polymer-coated glass beads were closely packed in a tubing of poly(vinyl chloride) (i.d. - 3 mm) equipped with a stopcock, and the packed column was primed with physiological saline for 24 h to exclude a liquid-air interface and to equilibrate the polymer surface with the physiological environment. 

The C1-C4 hydrocarbon gases are easily separated by a variety of packed columns. Most modern packing materials for this are based on synthetic porous polymers, or on porous silica beads of controlled texture (Chromosorbs 102, 104 Carbosphere, Hey Sep polymers, porapacks polymers, etc.). Both the analytical literature and the commercial catalogues offer many alternative materials which can be applied for gas-liquid and gas-solid chromatography. 

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