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LC_PH0498
Figure 2 Ultra II® Aqueous C18 columns outperform conventional C18 columns for
the analysis of organic acids in a 100% aqueous mobile phase.
Peak List
1. tartaric acid
2. quinic acid
3. malic acid
4. citric acid
5. fumaric acid
Sample: Inj.: 5µL; Conc.: 10µg/mL fumaric acid, 2,000µg/mL each other acids; Sample diluent: water; Column: Ultra II® Aqueous
C18; Cat.#: 9608565; Dimensions: 150mm x 4.6mm; Particle size: 5µm; Mobile phase: 100% 20mM potassium phosphate (pH
2.5); Det.: UV @ 226nm Complete analytical conditions for chromatogram LC_PH0498 available at
Better for Organic Acids—More Retentive, Selective and Stable than a C18
Aqueous C18 columns are also an excellent choice for analyzing organic acids. For
example, in Figure 2, an Ultra II® Aqueous C18 column provides greater retention and
selectivity for organic acids than a conventional C18. The unique bonding chemistry of
an Aqueous C18 column improves the retention of polar compounds and allows 100%
aqueous mobile phases to be used, making it an excellent choice when developing
methods for dietary supplement testing.
For the complete version of this condensed article, visit
LC_FF0432
LC_FF0431
Conventional C18 is less
retentive and selective
for organic acids.
Aqueous C18 exhibits
better retention, selectivity,
and no de-wetting.
Conventional C18 is prone
to de-wetting, a complete
loss of retention.
Conditions used in A, B, and C were identical. De-wetting in Figure 1C was caused for illustrative purposes by releasing
column pressure.
Learning LINKS
Why use a reversed phase column
specifically designed for highly
aqueous mobile phases?
Learn why at
void time
A: Ultra II® Aqueous C18
B: Conventional C18, initial analysis
C: Conventional C18, post pressure release
void
time
citric acid 2,000µg/ml
fumaric acid 10*
malic acid 2,000
quinic acid 2,000
tartaric acid 2,000
*Fumaric acid is a trace impurity in malic acid, as well as an
added component of the mix. The amount of fumaric acid in malic
acid will not affect the stated concentration of malic acid, but can
represent a significant and variable deviation from the low con-
centration of fumaric acid stated to be in the mix. All other com-
ponents of the mix are at the specified concentration.
Quantity discounts not available.
Fruit Juice Organic Acid Standard
(5 components)
In water, 1mL/ampul
cat. # 35080 (ea.)
In water, 5mL/ampul
cat. # 35081 (ea.)
More dimensions available online.
Ultra II® Aqueous C18 Columns (USP L1)
Chromatographic Properties:
Highly retentive and selective for reversed phase separations
of polar analytes. Highly base-deactivated. Compatible with
highly aqueous (up to 100%) mobile phases.
Physical Characteristics:
particle size: 2.2µm, 3µm or
5µm, spherical
pore size: 100Å
carbon load: 15%
endcap: no
pH range: 2.5 to 7.5
temperature limit: 80°C
3.2mm ID 4.6mm ID
Length cat.# cat.#
3µm Columns
30mm 9608333 9608335
50mm 9608353 9608355
100mm 9608313 9608315
150mm 9608363 9608365
5µm Columns
30mm 9608533 9608535
50mm 9608553 9608555
100mm 9608513 9608515
150mm 9608563 9608565
200mm 9608523 9608525
250mm 9608573 9608575
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