Chromatographic performance coating efficiency

Stationary phases used in TLC are microparticulate sorbents with particle diameters of between 10 and 30/im. The smaller the mean particle size and the narrower the size range, the better the chromatographic performance in terms of band spreading (efficiency) and resolution (Topic D2). Thin-layer chromatography plates are prepared by coating sorbents onto rectangular plastic, aluminum or glass sheets in adherent uniform layers approximately 250/tm... 

Chromatographic Resolution. To optimize column-coating conditions and operating parameters glass capillary columns coated with various silicone-based stationary phases were tested with difficult-to-separate groups of PAH standards and Complex samples. The SE5 -coated columns performed excellently with respect to separation efficiency, column bleed and long-term stability. Other observers have had similar results with this... 

As reversed-phase high-performance liquid chromatography is the most common mode of HPLC, many efforts have been made by chromatographers to introduce hydrophobic moieties on the zirconia surface. Polybutadiene-coated zirconia (PBD-Zr02) was proven to be an excellent reversed-phase packing material.PBD-Zr02 has excellent pH and thermal stability and is efficient for... 

Cyclodextrins have previously been successfully employed in separation science. For instance, the partial separation and enrichment of optical and structural isomers as well as routine compounds based on selective precipitation with CDs have been reported [5,7-8]. Additionally, solutions of CDs have served as the mobile phase in a few thin-layer and high performance liquid chromatographic separations [5,9,10]. However, their most widespread application in chromatography has been as part of the stationary phase [5,6]. Various polymeric CD materials, CD gels or resins, as well as CD coated columns have been utilized as the stationary phases in the separation of many important classes of compounds [5,6,11-13]. Unfortunately, the use of these CD phases has been largely restricted to column or gas chromatography due to their low efficiency and/or poor mechanical strength [14-16]. 

This separation requires a long time, although it can be significantly shortened by coating ODS (octadecyl silica) with lipophilic crown ether derivatives [23]. However, the chromatographic efficiency of these separations does not meet today s requirements. The only advantage of this method is the ability to perform a very sensitive detection via electrical conductivity, because the eluent being used does not have an intrinsic conductance. 

Modern gas chromatography is most often performed with high efficiency capillary (open tubular) columns coated with a cross-linked polymeric stationary phase. We provide chromatographic data on the two most common cross-linked phases (Ref. 1). These data are useful for the interpretation of chromatograms, and for quality control and assurance. The retention indices presented in these tables were measured at 120 °C isothermaUy. Retention indices are temperature dependent the temperature dependence of the Kovats indices have been studied for many compounds (Ref. 2). For more extensive information on other cross-linked phases, other silicone phases, mesogenic phases, and solid sorbents, the reader is advised to consult Ref. 1. 

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