• 10 •
800-356-1688 •
2004vol. 3
Pinnacle
™
DBBase-DeactivatedHPLC
Columns
Effective Replacements for Hypersil
®
BDSColumns
by RebeccaWittrig, Ph.D., HPLCProduct MarketingManager,
and Vernon Bartlett, HPLC Innovations TeamManager
•Sharp, symmetric peaks for basic analytes.
•Excellent reproducibility, column-to-column and lot-to-lot.
•Chromatography equivalent toHypersil
®
BDSmaterial.
With Pinnacle
™
DB base-deactivated silica, we
have created an exceptional material for analy-
ses of basic compounds, matching or exceeding
the chromatographic performance of Hypersil
®
BDSmaterial. Pinnacle
™
DB silica and bonded
phase packings aremade through efficient
processes that ensure reproducible perform-
ance and reliable stock levels—we ship 90% of
all analytical columns orderedwithin 24 hours.
In Figure 1, peak symmetry for the basic com-
pound pyridine is noticeably better on the
Pinnacle
™
DB C18 column than on a typicalType
B C18 column, and the analysis time is shorter
bymore than 30%. You can expect similar
results if youmake your own comparisons.
Figure 2 shows how closelymatched the impor-
tant physical characteristics of particle size and
pore size distribution are for Pinnacle
™
DB and
Hypersil
®
BDSmaterials. Physical/chemical
characteristics of Pinnacle
™
DBpackings are
listed inTable I.
For certain physical parameters - most notably,
metals content - we intentionally deviate from
Hypersil
®
BDSmaterial, as Figure 3 shows.The
major difference in sodium content is especially
important, asmetal ions on the surface of silica
particles negatively affect peak symmetry and
otherwise interferewith chromatography, partic-
ularly for basic analytes. But, there is another
important problemwith silicas that have a high
metal content, especially sodium—they are
structurally inferior to silicas containing lesser
amounts of metals.To strengthen silica particles
containing high concentrations of sodium, some
manufacturers use an annealing process to
embed the sodium into the framework of the
particles. Although annealing imparts strength to
the particles, it destroys some of their useable
surface area. And, as the particles age or crack,
embedded ions are re-exposed. Deactivation for
bases is lost, and stability in highly aqueous
mobile phases erodes.
Ourmanufacturing process stripsmetals and
other impurities from the silica surface. By
removingmetals, rather than covering them, we
make amore rugged silica that does not need
annealing to impart strength. Peak shapes for
bases aremore consistent as the column ages,
and the potential lifetime for a Pinnacle
™
DB col-
umn is longer. Also, large pores (140Å) make
Pinnacle
™
DBmaterial an excellent choicewhen
youwant to shorten analysis time.
But - how do separations on Pinnacle
™
DB
columns andHypersil
®
BDS columns compare?
The chromatograms in Figures 4 and 5 are
analyses of a base/neutral test mix and an
acid/base test mix, respectively. Behavior of
each of these analyteswill vary, based on differ-
ences in carbon load, ligand density, degree of
base deactivation, endcapping, and exposed
metals. Columns that are similar for these char-
acteristics should provide similar chromatogra-
phy, and Figures 4 and 5 show Pinnacle
™
DB C18
columns andHypersil
®
BDS columns perform
nearly identically.
If you are looking for rugged, high-quality
columns for analyzing basic compounds, or as
replacements for Hypersil
®
BDS columns, and
youwant them supplied quickly and reliably,
Pinnacle
™
DB columns are the ideal answer. In
addition to the product quality you expect, you'll
receive Plus 1
™
service and prompt, expert tech-
nical helpwhen you deal with Restek.
Figure1
Superior peak symmetry for pyridine, anda
faster analysis, onaPinnacle™DBcolumn.
LC_0245
Sample:
Inj.:
5.0µL
Solvent:
mobile phase
Conditions:
Mobile phase: 20mM potassium phosphate, pH 7.0: acetonitrile
(80:20 v/v)
Flow:
1.0mL/min.
Temp.:
ambient
Det.:
UV@ 254nm
LC_0248
Peak List:
Conc.
1. uracil
5.0µg/mL
2. pyridine
0.1µL/mL
3. phenol
1.86mg/mL
Column:
Pinnacle
™
DBC18
Conventional C18
Cat.#:
9414565
n/a
Dimensions:
150 x 4.6mm
150 x 4.6mm
Particle size:
5µm
5µm
Pore size:
140Å
100Å
Figure2
Physical characteristicsof Pinnacle™DBsilicaandHypersil®BDS silicaare remarkably similar.
Table I
Physical/chemical characteristicsof Pinnacle™
DBpackings.
Particle:
5µm, spherical
Pore size:
140Å
Pore volume:
0.65mL/g
Carbon load:
C18—11%
C8—6%
Cyano—4%
Particle Size analysis
PinnacleDB Hypersil BDS
GeometricMean (µm):
4.81±1.20
4.89±1.70
ArithmeticMean (µm):
4.89±0.94
4.95±0.82
Median (µm):
4.69
4.81
Mode:
4.69
4.79
Max Diff. (%):
6.04
7.11
PinnacleDB
Hypersil BDS
ParticleSizeDistribution
PoreSizeDistribution
