Page 151 - Illustrated Pocket Dictionary of Chromatography

POLYMERIC BONDED PHASE 151

Three different sized thin-layer plates are shown: lower left 5 ¥ 20cm, center 10 ¥
10cm, and center top 20 ¥ 20cm. The sorbent is silica in each case. The rightmost
plate is reversed to show the glass support.

plate theory Originally developed by Martin and Singh to provide
a mathematical description of a chromatographic elution curve. Many
others have modified and added to this basic theory through the years.

polyacrylamide Produced from the copolymerization of acry-
lamide and N,N¢-methlenebisacrylamide. The resulting copolymer is a
porous material that is used as an aqueous size-exclusion chromato-
graphic support.
polymeric bonded phase A polymeric bonded phase has multi-
ple attachments through a single bonding site on the surface. This is
accomplished by using multifunctional silanes (e.g., trichloro- or tri-
alkylsilanes). The polymer is built out from the surface as follows: The
advantage of the polymeric phase over monomeric phases is that
the polymeric phase offers a higher level of hydrophobicity and a
lower number of accessible silanol groups. The disadvantages are
the greater mass transfer effect on peak broadening (C term in van
Deemter equation) and the overall poorer reproducibility between
batches.