2
6
10min.
1
2
3
1
2
3
Feature
Analyzes polar compounds by
reversed phase.
Analyzes polar, hydrophillic
materialswithout retention
time loss. Stable retention in
100% aqueousmobile phases.
TrueC18 alkyl bonded phase.
High-densityC18 ligand
coverage.
Unique secondary polar
characteristics.
Benefit
Retains compounds such as amino
acids andwater soluble vitamins
using simplemobile phases and
without derivitization.
Can analyze compounds that are
sparingly soluble in organic solvents.
Meets requirements of USPL1.
Similar selectivity as traditional C18
phases for neutral hydrophobic
compounds.
End-capping diminishes peak tailing
observed from exposed silanol sites
on the silica surface.
Ultra Aqueous C18
HPLCColumns
Achieve StableRetention in 100%
AqueousMobile Phase
At-a-Glance
Product
Information
fromRestek
Features&Benefits
800-356-1688
814-353-1300
Figure 1
TheUltra Aqueous C18 phase provides
a hydrophilic environment that prevents
chain folding.
TheUltraAqueous C18HPLC column provides reproducible retention times
and can be usedwith highly aqueousmobile phases, whichmay eliminate the
need for sample derivitization or ion pairing reagents. This column features a
trueC18 alkyl bonded phase, meeting the requirements of aUSPharmacopoeia
(USP) L1 stationary phase.
Many traditional C18 alkyl stationary phases exhibit a loss in retention over
timewhen exposed to highly aqueousmobile phases. This retention time loss is
evenmore pronounced if themobile phase flow is stopped and restarted. One
theory explaining this loss in retention is “chain folding,”where extremely
hydrophobic alkyl chains of a traditional C18 phase fold down upon the surface
of the silica to avoid the hydrophilic aqueousmobile phase environment. In
turn, the foldedC18 chains diminish the amount of hydrophobic interaction that
occurs between sample analytes and the stationary phase, resulting in a loss of
analyte retention.
Restek scientists however, use a novel bonding chemistry for theUltraAqueous
C18 column that results in polar groups at the silica surface. These surface
polar groups keep the alkyl stationary phase extended, and thuswetted by the
mobile phase—evenwhen using up to 100% aqueousmobile phases (Figure 1).
Additionally, although theUltraAqueous C18 column behaves similarly to a
traditional base-deactivatedC18 columnwhen analyzing neutral hydrophobic
compounds, it has enhanced retention and unique selectivity for polar and basic
compounds (Figure 2).
Peak List:
Conc. (mg/mL)
1.glycolic acid 5.4
2.malonic acid 4.2
3.acetic acid 7.8
4.maleic acid 0.06
Sample:
Sample dissolved
inmobile phase.
Column:
Ultra Aqueous C18
Catalog#:
9178565
Dimensions: 150x4.6mm
Particle Size: 5µm
Pore Size:
100Å
Conditions:
Mobile Phase:50mM potassium
phosphate, pH 2.5
FlowRate: 1.0mL/min.
Temp.:
25°C
Det.:
UV@210nm
Inj.:
10µL
0 1 2 3 4 5 6 7min.
1
2
3
4
A. initial
B. after 3 Days
LC_0142
LC_0143
Peak List:
1. uracil
2. pyridine
3. phenol
Conditions:
Mobile phase: 20mM potassium
phosphate, pH 7.0:
acetonitrile (80:20)
Flow:
1.0mL/min.
Temp:
25°C
Det.:
UV@ 254nm
Dimensions: 150 x 4.6mm
Particle size: 5µm
Pore size:
100Å
Figure 2
TheUltra Aqueous C18 column has enhanced
retention and unique selectivity for polar and
basic compounds.
Ultra Aqueous C18
Base-deactivated C18
