Column packing bonding chemistries

Sander and wise have proposed a test method to determine the bonding chemistry used to prepare octadecylsiloxane column packings based on the relative retention of three polycyclic aromatic hydrocarbons, benzo[a]pyrene (BaP), phenanthro-phenanthrene (PhPh), and l,2 3,4 5,6 7,8-tetrabenzonaphthalene (TBN) eluted with the mobile phase acetonitrile-water (85 15) [52,67,199,210]. On monomeric phases the test solutes elute in the... 

Silica packings are popular because they can withstand the high pressures generated when 10- to 30-cm columns packed with 3- to 10- im particles are used. Silica is abundant, inexpensive, and available in a variety of shapes, sizes, and degrees of porosity. In addition, functional groups can be readily bonded to the silanols, and the chemistry of the bonding reactions... 

FIPLC columns packed with high-purity, silica-based bonded phases continue to dominate the market. Modern columns yield more symmetric peaks for basic analytes (less silanophilic activity) and have better batch-to-batch reproducibility and longer lifetimes. Improved bonding chemistries have widened the usable pFI range from 2-8 to 1.5-10 or more. Although C8- and CIS-bonded phases remain the most common, other phases have become quite popular, including phenyl, cyano, and several polar-embedded phases (e.g., amide, carbamate). 

Kirkland, J. J., Glajch, J. L., and Farlee, R. D., Synthesis and characterization of highly stable bonded phases for high-performance liqnid chromatography column packings. Analytical Chemistry 1989, 61, 2-11. 

The silica-based SEC packings which are currently being employed were Introduced on the market in 1980 and there has since been very little improvement In their properties in terms of pore size distribution, particle size etc. Now, initiated by theoretical Investigations of the resolution of SEC columns, a new family of SEC packings Is beginning to be produced and marketed. The new packings are characterized by a particle size smaller than 5 / m, adequate porosity, and superior bonding chemistry. The Bio-Series 6F 250 column from DuPont de Nemours Is a typical example. However, the performance - with reference to resolution, analysis time and peak capacity — of this novel material has not yet been evaluated. 

In comparison, there are over 200 different varieties of commercial columns worldwide which meet the criteria of the USP LI column designation (a packing of octadecylsilane chemistry, chemically bonded to porous silica or ceramic microparticles, 3-10 nm in diameter). 

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