Regular column packings

The introduction of "fast HPLC" has proven to be particularly valuable in protein analysis. As stated earlier, assay time in RP-HPLC analysis of proteins is typically long compared to that for smaller organic molecules. We have evaluated the use of 0.6-cm ID x 4-cm columns packed with 3-um particles in the analysis of insulin by RP-HPLC for potency determination, related substances, and in peptide mapping (7). The use of the "fast column" allows considerable savings (40-60%) in analysis time, compared to the regular (0.46-cm ID x 25-cm) columns, without loss in resolving power. 

Columns are expensive and can get clogged easily if the sample, the solvent, or wear particles from the pump have not been filtered properly. There are two ways to protect the column. One is to use a precolumn and the other is to use another in-line filter between the injector and the column. The precolumn is a short section of column, about 5 cm long, packed with the same material as the regular column and attached immediately in front of it. This column acts as a filter and provides some separation as well. 

In order to obtain maximum efficiency the column must be evenly packed. The influence of particle size and regularity of packing on column performance has been discussed elsewhere (Chapter 2). While open tubular... 

Pellicular particles technical term for a synthetic HPLC column packing material consisting of microglass beads, 10-50 pm in diameter with a 2-3 pm surface film of active stationary phase material. These packings have only about 10% of the capacity of microporous materials but produce columns with greater separation efficiencies due to the very rapid equilibrium processes that occur with such regular particles and thin stationary phase films. 

Verver and van Swaaij [32] obtained their results in 0.1 x 0.1 m columns packed with regularly stacked elements specially developed for gas-solid trickle flow contactor. The authors reported significant heat transfer rates, with the number of transfer units from two to four for... 

Column with regular structured packing (Table 2-28). Specific surface 100-500 gas load factor 2-5 Pa trickle density ... 

The classification of polymer mesophases have been considered in many reports (P-70). On analyzing the published data there arises much controversy in the identification. In order to avoid confusion in terminology it is necessary to define the basic terms relating to polymer columnar mesophases before further discussion. Columnar polymer systems have both a correlation of the centers of gravity and molecular orientation, but have mesomorphic properties due to the conformational disorder both of the polymer back-bone and side chains. The structural unit of the polymeric columnar mesophase is a macromolecule. In columnar phases macromolecules form regular 2D-periodic arrays. The two-dimensional symmetry of the column packing and the parameters of two-dimensional lattice are strongly dependent on the form and dimensions of the cross-section of a polymer molecule. 

Currently, UPLC or high-pressure HPLC/UV detection using sub-2-/column packing material has the potential of 2-min gradient samples analysis times for IPCs (e.g., COR, impurity determination, or solution concentration). Waters Patrol UPLC offers in-line and off-line versions. Real-time in-line HPLC has not been used on a regular basis in development enviroments. Most reactors are sampled manually with analysis performed off-line. 

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