152
800-356-1688or 814-353-1300
HPLCCOLUMNS
Physical Characteristics
pH ranges and temperature limits: see product listings on pages listed here.
Column lifetimewill be shorter when operating at pH and/or temperature extremes.
ManagingHighBackpressure
Highbackpressure isoneof themost commonproblemsencountered inHPLCanalyses. Normal columnbackpressure is
observedafter anewcolumnhasbeen installedandequilibratedwithmobilephase. Unfortunately, thispressureoftenwill
increaseas thecolumn isusedbecauseparticles collecton thecolumn inlet frit. Theseparticles canbe sample impurities,
mobilephasecontaminants, ormaterials from the injectoror autosampler rotor seal.
Inaddition to increasingbackpressure, particleson the frit cancause splitpeaks, peak tailing, and, eventually, over-pressure
shut-down. In somecircumstances, theseproblems canbecorrectedbyback-flushing thecolumn. However, inmanycases the
result isanunusablecolumn.
Tominimizebackpressureproblems, all samplesandmobilephase solventsmustbe filteredbeforeuse, and rotor seals should
bechangedona routinebasis. Alongwith thesepreventivemeasures, it isadvisable touseprecolumn filters suchas the
Tridentguardcolumnprotection system, pages196-198. Particlesbuildupon the inexpensive, replaceable frit in the filter,
insteadof on thepermanent frit at thecolumn inlet.
tech
tip
Applications
Carbon
load (%)
Pore
Size (Å)
End
Cap?
Restek
HPLCColumn
Allure Biphenyl
Y
60
23
Multiple ring structure; excellent for aromatic and unsaturated compounds. Increased retention over
traditional phenyl phases.
Allure Silica
— 60
— Highly retentive phase for normal phase separation.
Ultra C18
Y
100
20
Ideal for anilines, barbiturates, carbonyls, fat-soluble vitamins, fatty acids, glycerides, phthalates, PTH amino acids,
steroids, other acids.
Ultra Aqueous C18
N
100
15
Ideal for analyses that require>90%water in themobile phase. Excellent for highlywater soluble
or poorly organic soluble compounds. Excellent for water-soluble vitamins and organic acids.
Ultra IBD
N
100
12
A polar group assists in deactivating surface silanols and contributes to unique separation selectivities for acids,
bases, zwitterions, and other polar compounds.
Ultra C8
Y
100
12 Selectivity and peak shape similar toUltra C18, but less hydrophobic retention.
Ultra C4
Y
100
9 Ideal for peptides and small proteins.
Ultra C1
— 100
5
Alternative selectivity toUltra C18 or C8 columns, especially for polar analytes. Shortest chain alkyl phase
available for reversed phase separations.
Ultra Cyano
Y
100
8 Excellent for basic pharmaceuticals, steroids (normal or reversed phase conditions), or other basic compounds.
Ultra Phenyl
Y
100
10 Ideal for fatty acids, polycyclic aromatic hydrocarbons, purines and pyrimidines, and polar aromatics.
Ultra Amino
N
100
2 Superior general purpose amino phase. Ideal for carbohydrates.
Ultra PFP
Y
100
7 Ideal for taxol and precursors, or halogenated compounds, amines, esters, or ketones.
Ultra Silica
— 100
— Ideal for normal phase applications.
Ultra Carbamate
— 100
— Rapid analysis of carbamates.
UltraQuat
— 100
— Proprietary phase for the analysis of paraquat and diquat and other quaternary amines.
VivaWide Pore C18
Y
300
9 Proteins and other highermolecular weight compounds.
VivaWide Pore C8
Y
300
5 Proteins and other highermolecular weight compounds. Less retentive than C18 phase.
VivaWide Pore C4
Y
300
3.5 Proteins and other highermolecular weight compounds. Less retentive than C18 and C8 phases.
VivaWide Pore
Biphenyl
Y
300
6.7 Exhibits excellent peak shape for awide range of compounds; ideal for largemolecule and biomolecule assays.
VivaWide Pore
PFPPropyl
Y
300
5
Exhibits excellent peak shape for awide range of compounds, including nucleosides, nucleotides,
and halogenated compounds.
VivaWide Pore Silica — 300
— Normal phase applications for highly retained highmolecular weight compounds.
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Mar 2011
