Reversed-phase HPLC columns have been widely
used due to their superior resolution, high theoretical plate
number, ease of use and good cost performance.
Octadecyl silica gel (C18, ODS)
is the most commonly used by chromatographers. In reversed phase
HPLC columns, hydrophobic interaction is the dominant separation
mode. For some substances similar in hydrophobicity, recognition
capability may be poor, resulting in insufficient separation.
The COSMOSIL PYE and NPE columns utilize various
interactions based on electrons
of the stationary phase. The PYE and NPE columns can be widely
used for the separation of substances similar in structure.
Characteristics
The COSMOSIL PYE column is a reversed phase column. Its stationary
phase is planar pyrene or 2-(1-pyrenyl)ethyl groups bonded
chemically to the silica gel. Utilizing -
interactions originating from the pyrene ring, the PYE column
separates substances similar in structure.
The COSMOSIL NPE column is also a reversed phase column, which
contains nitrophenylethyl groups chemically bonded to the silica
gel. The NPE column provides unique retention characteristics
somewhat different from the PYE column, utilizing both
dipole-dipole and -
interactions.
Stationary phases and
interactions
Hydrophobic interaction -
interaction
Charge transfer interaction
Stereo selectivity
PYE STATIONARY PHASE
Hydrophobic interaction -
interaction
Charge transfer interaction
Dipole-dipole interaction
NPE STATIONARY PHASE
Material characteristics
COSMOSIL
5PYE
COSMOSIL
5NPE
Silica
gel
high purity spherical
porous silica
Average
particle size
5µm
Average
pore size
approx. 120Å
Specific
surface area
approx. 300m²/g
Stationary
phase
2-(1-pyrenyl)ethyl group
nitrophenylethyl group
End
capping treatment
near-perfect
treatment
Carbon
content
approx. 18%
approx. 9%
Separation of PAHs
C18 columns have been commonly used for the separation
of polycyclic aromatic hydrocarbons. However, their resolution for
the separation of isomers is limited. Due to the electrostatic
interaction between the sample ( eg. benz[α]anthracene and
chrysene) and the pyrene ring in the stationary phase, the
COSMOSIL PYE packed column can achieve the separation of aromatic
isomers.
electrons
of the stationary phase. The PYE and NPE columns can be widely
used for the separation of substances similar in structure.
