Polybutadiene -coated zirconia phase

J. Dai, X. Yang, and P. Carr, Comparison of the chromatography of octadecyl silane bonded silica and polybutadiene-coated zirconia phases based on a diverse set of cationic drugs, J. Chromatogr. A 1005 (2003), 63-82. 

Li, J. and Carr, P. W., Retention characteristics of polybutadiene-coated zirconia and comparison to conventional bonded phases, Anal. Chem., 68(17), 2857,... 

Li, J., Hu, Y. and Carr, P.W., Fast separations at elevated temperatures on polybutadiene-coated zirconia reversed-phase material, Anal. Chem., 69(19), 3884, 1997. 

J. Li and P. W. Carr, A study of the efficiency of polybutadiene-coated zirconia as a reversed-phase chromatographic support, Anal. Chem. 69 (1997), 2193-2201. 

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... 

A separation of the EPAjg was achieved using a 10 cm X 4.6 mm i.d. polybutadiene-coated zirconia (2.5-/rm particle size) reversed-phase column. Resolution and retention times were compared for this column at 30°C and at 100°C. The separation at 30°C and 1 ml min required 70 min while at 100°C and 3 ml min it was achieved in less than 4 min. Two isomeric pairs (B[a]A/CHY and B[b]F/B[k]F) were not resolved at either temperature, but peak symmetry was superior at the higher temperature and flow rate. ACE and FLU were also not resolved under the fast conditions. 

Carr and others have described the preparation and properties of polybutadiene (PBD) and polyethyleneimine (PEI), as well as aromatic polymer-coated and carbon-clad zirconia-based RP phases. The preparation of PBD-coated zirconia and the chromatographic evaluation of these phases have been described extensively by Carr, McNeff, and others [39 1]. From these studies, the authors conclude that at least for neutral analytes PBD zirconia-coated phases behave quite similar with respect to retention and efficiency compared to silica-based RP phases [42]. For polar and ionic analytes, however, substantial differences with respect to retention, selectivity, and efficiency have been reported [43]. 

One of the most interesting thermally stable groups of stationary phase materials has been the polybutadiene, carbon and phenyl-coated zirconia... 

Superheated water at 100°-240 °C, with its obvious benefits of low cost and low toxicity, was proposed as a solvent for reversed-phase chromatography.59 Hydrophobic compounds such as parabens, sulfonamides, and barbiturates were separated rapidly on poly(styrene-divinyl benzene) and graphitic phases. Elution of simple aromatic compounds with acetonitrile-water heated at 30°-130 °C was studied on coupled colums of zirconia coated with polybutadiene and carbon.60 The retention order on the polybutadiene phase is essentially uncorrelated to that on the carbon phase, so adjusting the temperature of one of the columns allows the resolution of critical pairs of... 

The other possibility is to coat the silica with a polymer of defined properties (molecular weight and distribntion) and olefin groups, e.g., polybutadiene, and cross-linked either by radiation or with a radical starter dissolved in the polymer [32]. This method is preferentially used when other carriers like titania and zirconia have to be surface modified. Polyethylenimine has been cross-linked at the snrface with pentaerythrolglycidether [41] to yield phases for protein and peptide chromatography. Polysiloxanes can be thermally bonded to the silica surface. Other technologies developed in coating fnsed silica capillaries in GC (polysiloxanes with SiH bonds) can also be applied to prepare RP for HPLC. 

Zirconia ZrO2 has similar properties as titania but can also interact with the analytes by ligand exchange because it is a Lewis acid. Chemical derivatization is possible. Coating with polybutadiene or polystyrene gives phases which are stable over a pH range of at least 1-13 and at temperatures higher than 200 °C. 

Porous zirconia particles coated with polybutadiene make a reversed-phase HPLC column packing that offers both excellent pressure stability and chemical inertness throughout the entire pH range. Because of the complex surface chemistry of zirconia, mobile phase additives such as phosphate or fluoride are added to facilitate the separa-... 

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