Column length high-speed

Accdg to our translation from the Russian, the critical density (pc) may be defined as the lowest value of loading density, p, at which a detonation wave will propagate thru full length of expl column at steady rate. Smallest further decrease in p will cause failure of detonation. The lowest deton velocity at this point, as registered by high-speed photography, may be considered as critical velocity and the density as critical pc (Ref 8, pp 292-93)... 

High-speed columns yield 5000-10,000 plates per meter, whereas most high-resolution columns give 3000-5000 plates per meter. Most applications of capillary columns are with column lengths of 10-50 m and are somewhat dependent on the complexity of the sample and the number of components of interest. A general rule is that samples with 20-50 components are best handled on columns of 20-30 m, whereas samples of 50 or more components will require 30-50 m of column. 

Column dimensions depend on the intended use and the most frequent commercial configurations are listed in Table LI. Generally, the column plate number, the pressure drop across the column and the separation time at a constant flow rate are directly proportional to the column length. The allowed sample amount which can be separated without column overloading increases with the second power of the column diameter as does the flow rate and the consumption of the mobile phase at a constant flow rate. Most separations are performed on conventional analytical columns, 10-25 cm long, 3-4.6 mm in diameter, packed with 5 pm (less frequently 3, 7 or 10 pm) particles. With so-called high-speed columns of the same diameter, but 3-6 cm long, simple separations can be accomplished in 1-3 min so that the productivity of the laboratory is considerably increased and solvent consumption per analysis reduced. 

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