High performance liquid chromatography stationary phases can separate polar and nonpolar compounds using reversed-phase or normal phase columns. Aqueous normal phase chromatography uses silicon-hydride stationary phases to retain both polar and nonpolar analytes in a single isocratic run through dual retention mechanisms. This distinguishes it from other chromatographic methods that can only separate compounds of specific polarities.

1. High performance liquid chromatography(HPLC) stationary phases can be segregated bytheir ability to separate
either polar on nonpolar compounds,thatis,reversed-phase materials (C18,C8) stronglyretain nonpolar solutes
with polarsolutes eluting ator near the void volume, and hydrophilic interaction.
The Pauling electronegativity of Carbon is 2.55 and Hydrogen is 2.2. Due to the small difference,.35,and the
definition of a polar bond, C-H bonds are considered nonpolar.
As carbon chains get longer, the molecules become less and less polar and hence less attracted to water molecules
than the water molecules are to each other.Carbon chain is hydrophobic part of molecule.... Carbon
chains are nonpolarwhereas water is polar,hence carbon chain are liked by water.
Ultra C8 Columns (USP L7)
Excellent for a wide range of analyses
Stationary Phase Category: C8, octylsilane (L7)
Ligand Type: monomeric C8
Particle: 3 μm or 5 μm, spherical
Pore Size: 100 Å
Carbon Load: 12%
End-Cap: yes
Surface Area: 300 m2
/g
pH Range: 2.5 to 8
Maximum Temperature: 80 °C
Similar Phase(s):
Eclipse Plus C8, Hypersil Gold C8, Luna C8, Symmetry C8,
Zorbax Eclipse XDB C8
Roc C18 HPLC Columns (USP L1)
 Conventional HPLC column built to be the
cornerstone for yourlab; pressure rated for any 400
bar HPLC system.
 Solid and reliable—delivers the peak shape,
reproducibility, ruggedness, and performance you
demand.
 Exceptional value for routine analyses and large-
volume w orkflows—high-purity, fully poroussilica
backed by quality manufacturing features a variety of
phases to fit most HPLC methods.
 Ideal for a w ide range of applications fromfood to
pharma;
5 phases cover 98% of USP methods.
Similar Phase(s):
Hypersil Gold C18, Luna C18, Reliant C18, Symmetry C18,
Zorbax Eclipse C18, Zorbax Eclipse XDB C18
Merck offers a comprehensive rangeof high-quality HPLC columns. Amongthese are a wide selection of columnsthat meetUSP (United
StatesPharmacopoeia) specifications. The L nomenclature wasintroduced by the USP to designate column typ esfor high-performance
liquidchromatography. To helpyou select the appropriateHPLC column for your application, the table below describesvarious L columnsas
well asthe corresponding HPLC columnsavailablefrom Merck.
USP Description Columns
L7
Octyl silane (C8) chemically bondedto
poroussilica particles, 1.5 to 10 µm in
diameter
Chromolith® RP-8 Endcapped
LiChrosorb® RP-8 (5 µm)
LiChrosorb® RP-8 (10 µm)
LiChrospher® RP-8 (5 µm)
LiChrospher® RP-8 (10 µm)
LiChrospher® RP-8 endcapped (5 µm)
LiChrospher® RP-Select B (5 µm)
LiChrospher® RP-Select B (10 µm)
Purospher® STAR RP-8 Endcapped (3 µm)
Purospher® STAR RP-8 Endcapped (5 µm)
Superspher® 60 RP-8 (4 µm)
Superspher® 60 RP-8 Endcapped (4 µm)
Superspher® 60 RP-Select B (4 µ

2. L1 Octadecylsilane
Merck offers a comprehensive rangeof high-quality HPLC columns. Amongthese are a wide selection of columnsthat meetUSP (United
StatesPharmacopoeia) specifications. The L nomenclature wasintroduced by the USP to designate column typesfor high-performance
liquidchromatography. To helpyou select the appropriateHPLC column for your application, the table below describesvarious L columnsas
well asthe corresponding HPLC columnsavailablefrom Merck.
USP Description Columns
L1
Octadecly silane(ODS or
C18) chemically bonded
to poroussilica or
ceramic particles, 1.5 to
10 µm in diameter
Chromolith® RP-18 Endcapped
LiChrosorb® RP-18 (5 µm)
LiChrosorb® RP-18 (10 µm)
LiChrospher® RP-18 (5 µm)
LiChrospher® RP-18 (10 µm)
LiChrospher® RP-18 Endcapped(5 µm)
LiChrospher® RP-18 Endcapped(10 µm)
Purospher® RP-18 (5 µm)
Purospher® RP-18 Endcapped (5 µm)
Purospher® STAR RP-18 Endcapped (3 µm)
Purospher® STAR RP-18 Endcapped (5 µm)
Superspher® RP-18 Endcapped (4 µm)
Superspher® RP-18 (4 µm)
High performance liquid chromatography (HPLC) stationary phases can be segregated by their ability to
separate either polar on nonpolar compounds, that is, reversed-phase materials (C18, C8) strongly retain
nonpolar solutes with polar solutes eluting at or near the void volume, and hydrophilic interaction
chromatography (HILIC) and normal phase columns strongly retain polar analytes with nonpolar compounds
being essentially nonretained (1). Increasingly, many analyses such as those encountered in drug discovery,
proteomics, and metabolomics can be more complex with solutes encompassing a broad range of polarities. To
overcome these deficiencies in column performance, more complex schemes of analysis might have to be
devised to provide successfully qualitative and quantitative information about solutes with differing
hydrophobicities and hydrophilicities. These approaches can include various types of sample preparation or
two-dimensional chromatographic methods (2) as well as using chromatographic extremes of pH (3) and
temperature (4). In most cases, such methodology can be cumbersome, time consuming, and damaging to
your instrument and the HPLC column. In many instances, it would be desirable to have a stationary phase that
can retain both polar and nonpolar compounds in an isocratic run so that a single separation strategy can be
devised to analyze samples with a broad range of polarities.
Recently, a third type of chromatographic strategy has been developed on stationary phases utilizing silicon-
hydride-based particles with a bonded phase (5–15). It is referred to as aqueous normal phase (ANP)
chromatography. The principle of ANP chromatography is simple: retention behavior is analogous to that found
in normal phase chromatography but the mobile phase has some water as part of the binary solvent. "Normal
phase" implies that retention is greatest for polar solutes such as acids and bases. In addition, retention must
increase as the amount of the nonpolar solvent in the mobile phase increases. So if the mobile phase consists
of water and acetonitrile, retention increases as the amount of acetonitrile increases. Typically, in ANP
chromatography, the amount of the nonpolar component in the mobile phase must be 60% or greater with the
exact point of increased retention depending upon the solute and the organic component of the mobile phase.
If a stationary phase had the retention properties previously described and could only separate polar solutes,
then it would be similar to a HILIC material (16–18). The term ANP is useful in distinguishing the hydride-based
phases from typical HILIC phases. The hydride stationary phases also can retain nonpolar compounds by a
traditional reversed-phase mechanism during the same isocratic run as described previously. Therefore, it is
this dual retention capability that distinguishes the silicon-hydride material from other silica-based HPLC
stationary phases. ANP chromatography is a useful term for indicating retention of ionizable–polar compounds
on a silicon-hydride stationary phase also possessing reversed-phase capabilities — as opposed to a HILIC
process that can separate only polar solutes.

3. SiliaChrom Plus - Reversed Phases HPLC Columns
> back to SiliaChrom Plus main page
All columns are offered in 3, 5 & 10 µm particle size.
Available phases:
 C18 (100 Å & 300 Å)
 dt C18 (100 Å)
 C8 (100 Å & 300 Å)
 C4 (100 Å & 300 Å)
 Cyano (100 Å)
 Pentafluorophenyl / PFP (120 Å)
 Phenyl (100 Å)
HPLC Column Particle
Size
Pore
Size
Specific Surface
Area
Carbon
Load
pH
Range
USP
Code
Temp.
Limit
Pressure
Limit
SiliaChrom Plus C18 > 3 μm
> 5 μm
> 10 μm
100 Å 370 - 430 m2
/g 15 % 2.0 - 8.0 L1 60°C 5,500 psi
SiliaChrom dt C18 > 3 μm
> 5 μm
> 10 μm
100 Å 410 - 440 m2
/g 18 % 1.5 - 9.0 L1 60°C 5,000 psi
SiliaChrom Plus C18-300 > 3 μm
> 5 μm
> 10 μm
300 Å 80 - 120 m2
/g 8 % 2.0 - 8.0 L1 60°C 4,000 psi
SiliaChrom Plus C8 > 3 μm
> 5 μm
> 10 μm
100 Å 370 - 430 m2
/g 8 % 2.0 - 8.0 L7 60°C 5,500 psi
SiliaChrom Plus C8-300 > 3 μm
> 5 μm
> 10 μm
300 Å 80 - 120 m2
/g 5 % 2.0 - 8.0 L7 60°C 4,000 psi
SiliaChrom Plus C4 > 3 μm
> 5 μm
> 10 μm
100 Å 370 - 430 m2
/g 6 % 2.0 - 8.0 L26 60°C 5,500 psi
SiliaChrom Plus C4-300 > 3 μm
> 5 μm
> 10 μm
300 Å 80 - 120 m2
/g 3 % 2.0 - 8.0 L26 60°C 4,000 psi
SiliaChrom Plus PFP > 3 μm
> 5 μm
> 10 μm
120 Å 320 - 360 m2
/g 9 % 2.0 - 8.0 L43 60°C 5,500 psi
SiliaChrom Plus Phenyl > 3 μm
> 5 μm
> 10 μm
100 Å 370 - 430 m2
/g 7 % 2.0 - 8.0 L11 60°C 5,500 psi
SiliaChrom Plus Cyano > 3 μm
> 5 μm
> 10 μm
100 Å 370 - 430 m2
/g 7 % 2.0 - 8.0 L10 60°C 5,500 psi

4. 30 Item(s)