Column packings nonporous

The nonporous spherical gels for PCHdC are often specially prepared for research purposes. However, nonporous polystyrene/divinylbenzene beads. Solid Bead, can be obtained in various particle sizes from Jordi Associates, Inc. (Bellingham, MA). Columns packed with these gels can be used for HdC of the polymers that are currently analyzed using polystyrene/divinylbenzene SEC columns. Fumed silica nanospheres are offered by Cabot (Tuscola, IL) (17), and nonporous silica (NPS) microspheres are offered by Micra Scientific, Inc. (Northbrook, IL). These nonporous silica gels may also be used for HdC. 

Although most PCHdC studies are conducted using columns packed with nonporous gels, the hydrodynamic separation also occur in SEC columns. This can be easily observed using small pore-size SEC columns (29) as shown in... 

Oostervink, R., Kraak, J.C., and Poppe, H., Hydrodynamic chromatography of soluble macromolecules of columns packed with submicron nonporous silica particles, Am. Lab., 30(6), 24C, 1998. 

This method is used particularly for colloids. A colloidal dispersion is forced through a long column packed with nonporous beads with an approximate radius of 10pm. Particles of different particle size travel with different speeds around the beads and are thus collected in size fractions. 

In the case of chromatographic columns packed with spherical nonporous adsorbent particles the differential mass transfer balance can be described by... 

The experimental of peptides or proteins depend more on the type of the column than on the gradient program and are constant within % at various gradient times. The variance in the (p is lower as the size of molecules increases. The values of (p are slightly higher with totally porous particles than with columns packed with superficially porous, nonporous particles and monolithic columns [97]. 

The power of fluorescence detection was illustrated on the separation of PAH s by Yan et al. [64]. The 16 U.S. EPA priority PAHs were separated in isocratic mode in less then 10 min using 100 pm I.D. columns packed with 1.5 pm nonporous octadecyl silica particles. Separation efficiencies of 750,000 plates/m were obtained when the PAHs were detected by ICFD while 300,000-400,000 plates/m were found for OCFD. 

The accurate prediction of the elution profiles for polypeptide(s) or protein(s) from columns packed with nonporous and porous adsorbents represents a much more significant challenge. In the case of the use of nonporous sorbents in packed beds, an analytical solution can again be obtained. For porous adsorbents in packed beds, a sectional adsorption model (SAM), based on the (hypothetical) ability to treat the bed as a series of tanks-in-series has found wide application. 

Figure 28 Capillary electrochromatography of four t-RNAs. Capillary column, packed with 2-pm nonporous ODSS stationary phase, 20.5/27 cm x 100 pm i.d. running voltage, 20 kV, electrokinetic injection, 1 kV for 2 s mobile phase in (a), hydroorganic eluent containing 1 5 mM phosphate and composed of 40% (v/v) methanol. Solutes 1, t-RNAGIU 2 t-RNAVal 3, t-RNALys 4, t-RNAphe. (Reprinted from Ref. 119, with permission.)...

Columns packed with nonporous particles have also been available on the market for more than 10 years. These columns do not have bimodal overall... 

Isocratic separation of test compounds is a useful way to demonstrate the performance of a system. Basic chromatographic characteristics, such as theoretical plates, are easily measured and can be compared to what is expected from theory and to performance of other chromatographic systems. Figure 17-4 is a UHPLC chromatogram obtained under isocratic conditions on a 43-cm-long capillary column packed with 1.0-pm nonporous Cl 8 particles (Eichrom... 

Figure 17-4. Chromatogram obtained on a column packed with l.O-pm nonporous particles at a run pressure of 3000 bar. (Reprinted from reference 37, with permission.)...

Figure 17-7. Base peak index chromatogram of BSA digest on 150- xm x 22-cm column packed with 1.5- xm nonporous CIS silica particles. (Reprinted from reference 34, with permission from American Chemical Society.)...

Leroy, F., Presle, B., Verillon, F. and Verette, E. Fast generic-gradient reversed-phase high-performance liquid chromatography using short narrow-bore columns packed with small nonporous silica particles for the analysis of combinatorial libraries. ]. Chromatogr. Sci. 39 487-490, 2001. 

The HPLC of large biomolecules such as proteins and DNA often requires specialized columns packed with wide-pore polymer or silica-based bonded phase with extra-low silanol activity.1215 Alternate approaches are pellicular materials or very small nonporous particles. Some of these columns are packed in PEEK or titanium hardware to allow the use of high-salt mobile phase and to prevent possible protein denaturing by metallic leachates. Further details on bio-separations and application examples are discussed in Chapter 7. 

Figure 7.33. HPLC analysis of nuclei acids (pBR322-DNA HAE-III digest) using gradient weak-anion exchange chromatography on a column packed with 2.5-pm nonporous polymer support (weak anion exchange) with UV detection at 260nm. Reprinted with permission from reference 40.

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