Page 179 - Illustrated Pocket Dictionary of Chromatography

SNELL’S LAW (OF REFRACTION) 181

permeation (e.g., polystyrene divinylbenzene support) and gel filtra-
tion (e.g., silica support). The important characteristic in any SEC
method is the there is no adsorption or partitioning of the analyte onto
the support surface; all separation is due to accessing pore volume or
not.
skew See asymmetry.

slurry packing To reproducibly and effectively place packing
material into columns of narrow inner diameter, the packing material
is often suspended in a solvent and then pumped under high pressure
into the column. This is slurry packing.

To generate a well-packed and highly efficient HPLC column dry packing is unac-
ceptable. Therefore, packing material is suspended in solution and pumped at high
pressure into the column tube. This picture shows one configuration for upward
slurry column packing. The slurries packing material is placed in the lower “bomb,”
which is sealed. The analytical column (top column) is connected above the bomb
with a spacer column and is terminated with a fritted endfitting. High pressure is
built up with no flow and then released to rapidly pack the column.

Snell’s law (of refraction) Snell’s law mathematically describes
the relationship between the angles of incidence, f 1, and the angle
of refraction, f 2, for substances with refractive indices of n 1 and n 2,
respectively: