800-356-1688or 814-353-1300
155
HPLCCOLUMNS
USLC™
EvaluatingandExtendingSelectivity
Restek leads the industry in USLC™ phase diversity because optimal differences in selectivity are built in during the research and
developmentofourbondedphases.
The diversity in selectivity providedbyUSLC™ columns canbe demonstrated empirically using the hydrophobic-subtraction (HS)
model [1].Thismodel isanovelprocedure forcharacterizing selectivity thatuses testprobes todefine the soluteand stationaryphase
interactions in reversed phase separations. Restek is leading the commercial application of this model by implementing it in the
research and development of USLC™ bonded phases. To evaluate phase selectivity using the hydrophobic-subtractionmodel, the
retention characteristicsof the soluteprobes are comparedacrossdifferentphaseson the same silicabase. In this approach, the range
of selectivity is indicatedby the degree of scatter along the regression line; high correlations indicate similarity and low correlations
represent changes in selectivityacrossphases (Figure2).Thedifference in selectivityacross columns can thenbequantifiedbasedon
the correlationby calculating the selectivity (S) statistic for the comparison [2].
Figure2
Restekhas extended the selectivity range for reversedphase separations as illustratedby the
hydrophobic-subtractionmodel and corresponding selectivity (S) value.
USLC™Columns:SelectivityChoicesOptimizeSeparations
RestekUSLC™ columns offer the widest range of selectivities available and are an integral part of successful method development
(Figure 3). Ideal for column switching systems, these columns provide the orthogonal separations needed to create optimal resolu-
tion and robust methods. Combining USLC™ phases with a suitable column format gives practicing chromatographers themost
powerful tool available for successfulmethoddevelopment.
HSModelTestProbeRetentionAcrossUSLCPhases
r
2
=0.7138
0
2
4
6
8
10
12
0
2
4
6
8
10
12
14
k' C18phaseonUltra II
k'Orthogonal phaseonUltra II
Ultra II PFPP
Ultra II Biphenyl
Ultra II IBD
Ultra IIAqueousC18
Highdegreeof scatter indicates
greaterdifferences in selectivity.
Selectivity (S)=100x 1-r
2
S=53.5
We’rehere tohelp!
Todiscuss the right selectivity for your separationor to findacomparable
column,
contactusatsupport@restek.comor800-356-1688.
References (Not available fromRestek.)
[1] L.R. Snyder, J.W. Dolan, P.W. Carr, J. Chromatogr. A 1060 (2004) 77.
[2]U.D. Neue, J.E. O’Gara, A. Mendez, J. Chromatogr. A 1127 (2006) 161.
Figure3:
Restekoffers thewidest rangeof selectivephasesavailableonanycolumn line.
ColumnLine
Common
ReversedPhase
ColumnType
RestekUltra II
1.9, 2.2, 3, 5and
10μm
Waters
AcquityCSH
1.7, 3.5and5μm
Waters
AcquityHSS
1.8, 3.5and5μm
Waters
AcquityBEH
1.7, 2.5, 3.5, 5and
10μm
Phenomenex
Kinetex
1.7and2.6μm
Agilent
ZorbaxRRHD
1.8, 3.5and5μm
Agilent
Poroshell 120
2.7μm
Alkyl
(C18andC8)
•
•
•
•
•
•
•
Phenyl
•
•
•
PolarEmbedded
Alkyl
•
Fluorophenyl
•
•
•
Website :
E-mail :
TelNo : 03 9762 2034 . . . inAUSTRALIA
Mar 2011
