1
2
3
4
0
1
2
3
4
5 min.
1
2
3
4
0
1
2
3
4
5 min.
Figure3
Hydrophobic compounds are retained similarly on theUltraAqueousC18and the conventionalUltraC18 columns.
Figure4
UltraAqueousC18 column provides enhanced retention of pyridine and shows a high level of base deactivation.
GreaterRetentionandSharperPeakShapeofPolar
Compounds
TheUltraAqueousC18 column typicallyhas very similar
retention and selectivity to themore conventionalUltraC18
columnwhenanalyzingneutral, hydrophobiccompounds
(Figure3). TheUltraC18 column is ahighly retentive,well-
deactivated, general purposeC18 column.Theuniquequalities
of theUltraAqueousC18 column are apparent, however,when
separatingpolar compounds (Figure4).Althoughphenol, a
neutral polar compound, is retained similarlybyboth columns,
basic andmorepolar pyridinehas approximately2.5 timesmore
retentionon theUltraAqueousC18 column.
Alsonote the relatively symmetrical peak shapeof pyridine
using theUltraAqueousC18 column; thepeak symmetryof
pyridine is commonlyused as a test probe for columnbase
deactivation. Someolder generationC18columns enhanced their
retentionof polar compoundsusing low-coveragebonding,
which left a large populationof active silanols on the silica
LC_0143
PeakList:
Conc.
(mg/mL)
1. uracil
0.02
2. benzene
3.00
3. naphthalene
0.50
4. biphenyl
0.06
Conditions:
Mobile phase: methanol:water (85:15, v/v)
Flow:
1.0mL/min.
Temp.:
ambient
Det.:
UV@254nm
Sample:
Inj.:
5µL
Solvent:
methanol:water (75:25)
LC_0145
RestekCorporation • (800)356-1688 • (814) 353-1300 •
PeakList:
1. uracil
2. pyridine
3. phenol
Conditions:
Mobile phase: 20mMpotassium
phosphate, pH 7.0:
acetonitrile (80:20)
Flow:
1.0mL/min.
Temp:
25°C
Det.:
UV@254nm
UltraAqueousC18
(cat.#9178565)
Dimensions:
150x4.6mm;
Particle size:
5µm;
Pore size:
100Å
Base-deactivatedC18
Dimensions:
150x4.6mm;
Particle size:
5µm;
Pore size:
100Å
1
2
3
1
2
3
2
6
10 min.
2
6
10 min.
UltraAqueousC18
(cat.#9178565)
Dimensions:
150x4.6mm;
Particle size:
5µm;
Pore size:
100Å
UltraC18
(cat.#9174565)
Dimensions:
150x4.6mm;
Particle size:
5µm;
Pore size:
100Å
